8.7 Circumference and Area of Circles
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Lesson 3: Rectangles Inscribed in Circles
NYS COMMON CORE MATHEMATICS CURRICULUM Lesson 3 M5 GEOMETRY Lesson 3: Rectangles Inscribed in Circles Student Outcomes . Inscribe a rectangle in a circle. Understand the symmetries of inscribed rectangles across a diameter. Lesson Notes Have students use a compass and straightedge to locate the center of the circle provided. If necessary, remind students of their work in Module 1 on constructing a perpendicular to a segment and of their work in Lesson 1 in this module on Thales’ theorem. Standards addressed with this lesson are G-C.A.2 and G-C.A.3. Students should be made aware that figures are not drawn to scale. Classwork Scaffolding: Opening Exercise (9 minutes) Display steps to construct a perpendicular line at a point. Students follow the steps provided and use a compass and straightedge to find the center of a circle. This exercise reminds students about constructions previously . Draw a segment through the studied that are needed in this lesson and later in this module. point, and, using a compass, mark a point equidistant on Opening Exercise each side of the point. Using only a compass and straightedge, find the location of the center of the circle below. Label the endpoints of the Follow the steps provided. segment 퐴 and 퐵. Draw chord 푨푩̅̅̅̅. Draw circle 퐴 with center 퐴 . Construct a chord perpendicular to 푨푩̅̅̅̅ at and radius ̅퐴퐵̅̅̅. endpoint 푩. Draw circle 퐵 with center 퐵 . Mark the point of intersection of the perpendicular chord and the circle as point and radius ̅퐵퐴̅̅̅. 푪. Label the points of intersection . -
Squaring the Circle a Case Study in the History of Mathematics the Problem
Squaring the Circle A Case Study in the History of Mathematics The Problem Using only a compass and straightedge, construct for any given circle, a square with the same area as the circle. The general problem of constructing a square with the same area as a given figure is known as the Quadrature of that figure. So, we seek a quadrature of the circle. The Answer It has been known since 1822 that the quadrature of a circle with straightedge and compass is impossible. Notes: First of all we are not saying that a square of equal area does not exist. If the circle has area A, then a square with side √A clearly has the same area. Secondly, we are not saying that a quadrature of a circle is impossible, since it is possible, but not under the restriction of using only a straightedge and compass. Precursors It has been written, in many places, that the quadrature problem appears in one of the earliest extant mathematical sources, the Rhind Papyrus (~ 1650 B.C.). This is not really an accurate statement. If one means by the “quadrature of the circle” simply a quadrature by any means, then one is just asking for the determination of the area of a circle. This problem does appear in the Rhind Papyrus, but I consider it as just a precursor to the construction problem we are examining. The Rhind Papyrus The papyrus was found in Thebes (Luxor) in the ruins of a small building near the Ramesseum.1 It was purchased in 1858 in Egypt by the Scottish Egyptologist A. -
Circumference and Area of Circles 353
Circumference and 7-1 Area of Circles MAIN IDEA Find the circumference Measure and record the distance d across the circular and area of circles. part of an object, such as a battery or a can, through its center. New Vocabulary circle Place the object on a piece of paper. Mark the point center where the object touches the paper on both the object radius and on the paper. chord diameter Carefully roll the object so that it makes one complete circumference rotation. Then mark the paper again. pi Finally, measure the distance C between the marks. Math Online glencoe.com • Extra Examples • Personal Tutor • Self-Check Quiz in. 1234 56 1. What distance does C represent? C 2. Find the ratio _ for this object. d 3. Repeat the steps above for at least two other circular objects and compare the ratios of C to d. What do you observe? 4. Graph the data you collected as ordered pairs, (d, C). Then describe the graph. A circle is a set of points in a plane center radius circumference that are the same distance from a (r) (C) given point in the plane, called the center. The segment from the center diameter to any point on the circle is called (d) the radius. A chord is any segment with both endpoints on the circle. The diameter of a circle is twice its radius or d 2r. A diameter is a chord that passes = through the center. It is the longest chord. The distance around the circle is called the circumference. -
And Are Congruent Chords, So the Corresponding Arcs RS and ST Are Congruent
9-3 Arcs and Chords ALGEBRA Find the value of x. 3. SOLUTION: 1. In the same circle or in congruent circles, two minor SOLUTION: arcs are congruent if and only if their corresponding Arc ST is a minor arc, so m(arc ST) is equal to the chords are congruent. Since m(arc AB) = m(arc CD) measure of its related central angle or 93. = 127, arc AB arc CD and . and are congruent chords, so the corresponding arcs RS and ST are congruent. m(arc RS) = m(arc ST) and by substitution, x = 93. ANSWER: 93 ANSWER: 3 In , JK = 10 and . Find each measure. Round to the nearest hundredth. 2. SOLUTION: Since HG = 4 and FG = 4, and are 4. congruent chords and the corresponding arcs HG and FG are congruent. SOLUTION: m(arc HG) = m(arc FG) = x Radius is perpendicular to chord . So, by Arc HG, arc GF, and arc FH are adjacent arcs that Theorem 10.3, bisects arc JKL. Therefore, m(arc form the circle, so the sum of their measures is 360. JL) = m(arc LK). By substitution, m(arc JL) = or 67. ANSWER: 67 ANSWER: 70 eSolutions Manual - Powered by Cognero Page 1 9-3 Arcs and Chords 5. PQ ALGEBRA Find the value of x. SOLUTION: Draw radius and create right triangle PJQ. PM = 6 and since all radii of a circle are congruent, PJ = 6. Since the radius is perpendicular to , bisects by Theorem 10.3. So, JQ = (10) or 5. 7. Use the Pythagorean Theorem to find PQ. -
Squaring the Circle in Elliptic Geometry
Rose-Hulman Undergraduate Mathematics Journal Volume 18 Issue 2 Article 1 Squaring the Circle in Elliptic Geometry Noah Davis Aquinas College Kyle Jansens Aquinas College, [email protected] Follow this and additional works at: https://scholar.rose-hulman.edu/rhumj Recommended Citation Davis, Noah and Jansens, Kyle (2017) "Squaring the Circle in Elliptic Geometry," Rose-Hulman Undergraduate Mathematics Journal: Vol. 18 : Iss. 2 , Article 1. Available at: https://scholar.rose-hulman.edu/rhumj/vol18/iss2/1 Rose- Hulman Undergraduate Mathematics Journal squaring the circle in elliptic geometry Noah Davis a Kyle Jansensb Volume 18, No. 2, Fall 2017 Sponsored by Rose-Hulman Institute of Technology Department of Mathematics Terre Haute, IN 47803 a [email protected] Aquinas College b scholar.rose-hulman.edu/rhumj Aquinas College Rose-Hulman Undergraduate Mathematics Journal Volume 18, No. 2, Fall 2017 squaring the circle in elliptic geometry Noah Davis Kyle Jansens Abstract. Constructing a regular quadrilateral (square) and circle of equal area was proved impossible in Euclidean geometry in 1882. Hyperbolic geometry, however, allows this construction. In this article, we complete the story, providing and proving a construction for squaring the circle in elliptic geometry. We also find the same additional requirements as the hyperbolic case: only certain angle sizes work for the squares and only certain radius sizes work for the circles; and the square and circle constructions do not rely on each other. Acknowledgements: We thank the Mohler-Thompson Program for supporting our work in summer 2014. Page 2 RHIT Undergrad. Math. J., Vol. 18, No. 2 1 Introduction In the Rose-Hulman Undergraduate Math Journal, 15 1 2014, Noah Davis demonstrated the construction of a hyperbolic circle and hyperbolic square in the Poincar´edisk [1]. -
20. Geometry of the Circle (SC)
20. GEOMETRY OF THE CIRCLE PARTS OF THE CIRCLE Segments When we speak of a circle we may be referring to the plane figure itself or the boundary of the shape, called the circumference. In solving problems involving the circle, we must be familiar with several theorems. In order to understand these theorems, we review the names given to parts of a circle. Diameter and chord The region that is encompassed between an arc and a chord is called a segment. The region between the chord and the minor arc is called the minor segment. The region between the chord and the major arc is called the major segment. If the chord is a diameter, then both segments are equal and are called semi-circles. The straight line joining any two points on the circle is called a chord. Sectors A diameter is a chord that passes through the center of the circle. It is, therefore, the longest possible chord of a circle. In the diagram, O is the center of the circle, AB is a diameter and PQ is also a chord. Arcs The region that is enclosed by any two radii and an arc is called a sector. If the region is bounded by the two radii and a minor arc, then it is called the minor sector. www.faspassmaths.comIf the region is bounded by two radii and the major arc, it is called the major sector. An arc of a circle is the part of the circumference of the circle that is cut off by a chord. -
Geometry Course Outline
GEOMETRY COURSE OUTLINE Content Area Formative Assessment # of Lessons Days G0 INTRO AND CONSTRUCTION 12 G-CO Congruence 12, 13 G1 BASIC DEFINITIONS AND RIGID MOTION Representing and 20 G-CO Congruence 1, 2, 3, 4, 5, 6, 7, 8 Combining Transformations Analyzing Congruency Proofs G2 GEOMETRIC RELATIONSHIPS AND PROPERTIES Evaluating Statements 15 G-CO Congruence 9, 10, 11 About Length and Area G-C Circles 3 Inscribing and Circumscribing Right Triangles G3 SIMILARITY Geometry Problems: 20 G-SRT Similarity, Right Triangles, and Trigonometry 1, 2, 3, Circles and Triangles 4, 5 Proofs of the Pythagorean Theorem M1 GEOMETRIC MODELING 1 Solving Geometry 7 G-MG Modeling with Geometry 1, 2, 3 Problems: Floodlights G4 COORDINATE GEOMETRY Finding Equations of 15 G-GPE Expressing Geometric Properties with Equations 4, 5, Parallel and 6, 7 Perpendicular Lines G5 CIRCLES AND CONICS Equations of Circles 1 15 G-C Circles 1, 2, 5 Equations of Circles 2 G-GPE Expressing Geometric Properties with Equations 1, 2 Sectors of Circles G6 GEOMETRIC MEASUREMENTS AND DIMENSIONS Evaluating Statements 15 G-GMD 1, 3, 4 About Enlargements (2D & 3D) 2D Representations of 3D Objects G7 TRIONOMETRIC RATIOS Calculating Volumes of 15 G-SRT Similarity, Right Triangles, and Trigonometry 6, 7, 8 Compound Objects M2 GEOMETRIC MODELING 2 Modeling: Rolling Cups 10 G-MG Modeling with Geometry 1, 2, 3 TOTAL: 144 HIGH SCHOOL OVERVIEW Algebra 1 Geometry Algebra 2 A0 Introduction G0 Introduction and A0 Introduction Construction A1 Modeling With Functions G1 Basic Definitions and Rigid -
Symmetry of Graphs. Circles
Symmetry of graphs. Circles Symmetry of graphs. Circles 1 / 10 Today we will be interested in reflection across the x-axis, reflection across the y-axis and reflection across the origin. Reflection across y reflection across x reflection across (0; 0) Sends (x,y) to (-x,y) Sends (x,y) to (x,-y) Sends (x,y) to (-x,-y) Examples with Symmetry What is Symmetry? Take some geometrical object. It is called symmetric if some geometric move preserves it Symmetry of graphs. Circles 2 / 10 Reflection across y reflection across x reflection across (0; 0) Sends (x,y) to (-x,y) Sends (x,y) to (x,-y) Sends (x,y) to (-x,-y) Examples with Symmetry What is Symmetry? Take some geometrical object. It is called symmetric if some geometric move preserves it Today we will be interested in reflection across the x-axis, reflection across the y-axis and reflection across the origin. Symmetry of graphs. Circles 2 / 10 Sends (x,y) to (-x,y) Sends (x,y) to (x,-y) Sends (x,y) to (-x,-y) Examples with Symmetry What is Symmetry? Take some geometrical object. It is called symmetric if some geometric move preserves it Today we will be interested in reflection across the x-axis, reflection across the y-axis and reflection across the origin. Reflection across y reflection across x reflection across (0; 0) Symmetry of graphs. Circles 2 / 10 Sends (x,y) to (-x,y) Sends (x,y) to (x,-y) Sends (x,y) to (-x,-y) Examples with Symmetry What is Symmetry? Take some geometrical object. -
Unit 5 Area, the Pythagorean Theorem, and Volume Geometry
Unit 5 Area, the Pythagorean Theorem, and Volume Geometry ACC Unit Goals – Stage 1 Number of Days: 34 days 2/27/17 – 4/13/17 Unit Description: Deriving new formulas from previously discovered ones, the students will leave Unit 5 with an understanding of area and volume formulas for polygons, circles and their three-dimensional counterparts. Unit 5 seeks to have the students develop and describe a process whereby they are able to solve for areas and volumes in both procedural and applied contexts. Units of measurement are emphasized as a method of checking one’s approach to a solution. Using their study of circles from Unit 3, the students will dissect the Pythagorean Theorem. Through this they will develop properties of the special right triangles: 45°, 45°, 90° and 30°, 60°, 90°. Algebra skills from previous classes lead students to understand the connection between the distance formula and the Pythagorean Theorem. In all instances, surface area will be generated using the smaller pieces from which a given shape is constructed. The student will, again, derive new understandings from old ones. Materials: Construction tools, construction paper, patty paper, calculators, Desmos, rulers, glue sticks (optional), sets of geometric solids, pennies and dimes (Explore p. 458), string, protractors, paper clips, square, isometric and graph paper, sand or water, plastic dishpan Standards for Mathematical Transfer Goals Practice Students will be able to independently use their learning to… SMP 1 Make sense of problems • Make sense of never-before-seen problems and persevere in solving them. and persevere in solving • Construct viable arguments and critique the reasoning of others. -
On the Hawking Wormhole Horizon Entropy
ON THE HAWKING WORMHOLE HORIZON ENTROPY Hristu Culetu, Ovidius University, Dept.of Physics, B-dul Mamaia 124, 8700 Constanta, Romania e-mail : [email protected] November 11, 2018 Abstract The entropy S of the horizon θ = π/2 of the Hawking wormhole written in spherical Rindler coordinates is computed in this letter. Us- ing Padmanabhan’s prescription, we found that the surface gravity of the horizon is constant and equals the proper acceleration of the Rindler ob- server. S is a monotonic function of the radial coordinate ξ and vanishes when ξ equals the Planck length. In addition, its expression is similar with the Kaul-Majumdar one for the black hole entropy, including logarithmic corrections in quantum gravity scenarios. Keywords : surface gravity, spherical Rindler coordinates, horizon entropy. PACS Nos : 04.60 - m ; 02.40.-k ; 04.90.+e. 1 Introduction The connection between gravity and thermodynamics is one of the most sur- arXiv:hep-th/0409079v4 14 Apr 2006 prising features of gravity. Once the geometrical meaning of gravity is accepted, surfaces which act as one-way membranes for information will arise, leading to some connection with entropy, interpreted as the lack of information [1] [2]. As T.Padmanabhan has noticed [3], in any spacetime we might have a family of observers following a congruence of timelike curves which have no access to part of spacetime (a horizon is formed which blocks the informations from those observers). Keeping in mind that QFT does not recognize any nontrivial geometry of space- time in a local inertial frame, we could use a uniformly accelerated frame (a local Rindler frame) to study the connection between one way membranes arising in a spacetime and the thermodynamical entropy. -
The Method of Exhaustion
The method of exhaustion The method of exhaustion is a technique that the classical Greek mathematicians used to prove results that would now be dealt with by means of limits. It amounts to an early form of integral calculus. Almost all of Book XII of Euclid’s Elements is concerned with this technique, among other things to the area of circles, the volumes of tetrahedra, and the areas of spheres. I will look at the areas of circles, but start with Archimedes instead of Euclid. 1. Archimedes’ formula for the area of a circle We say that the area of a circle of radius r is πr2, but as I have said the Greeks didn’t have available to them the concept of a real number other than fractions, so this is not the way they would say it. Instead, almost all statements about area in Euclid, for example, is to say that one area is equal to another. For example, Euclid says that the area of two parallelograms of equal height and base is the same, rather than say that area is equal to the product of base and height. The way Archimedes formulated his Proposition about the area of a circle is that it is equal to the area of a triangle whose height is equal to it radius and whose base is equal to its circumference: (1/2)(r · 2πr) = πr2. There is something subtle here—this is essentially the first reference in Greek mathematics to the length of a curve, as opposed to the length of a polygon. -
COBE Satellite Measurement\ Hyperspheres\ Superstrings and the Dimension of Spacetime
Chaos\ Solitons + Fractals Vol[ 8\ No[ 7\ pp[ 0334Ð0360\ 0887 Þ 0887 Elsevier Science Ltd[ All rights reserved Pergamon Printed in Great Britain \ 9859Ð9668:87 ,08[99¦9[99 PII] S9859!9668"87#99019!8 COBE Satellite Measurement\ Hyperspheres\ Superstrings and the Dimension of Spacetime M[ S[ EL NASCHIE DAMTP\ Cambridge\ U[K[ "Accepted 10 April 0887# Abstract*The _rst part of the paper attempts to establish connections between hypersphere backing in in_nite dimensions\ the expectation value of dim E"# spacetime and the COBE measurement of the microwave background radiation[ One of the main results reported here is that the mean sphere in S"# spans a four dimensional manifold and is thus equal to the expectation value of the topological dimension of E"#[ In the second part we introduce within a general theory\ a probabolistic justi_cation for a com! pacti_cation which reduces an in_nite dimensional spacetime E"# "n# to a four dimensional one "# 2 "DTn3#[ The e}ective Hausdor} dimension of this space is given by ðdimH E ŁdH3¦f where f20:ð3¦f2Ł is a PV number and f"z4−0#:1 is the Golden Mean[ The derivation makes use of various results from knot theory\ four manifolds\ noncommutative geometry\ quasi periodic tiling and Fredholm operators[ In addition some relevant analogies between E"#\ statistical mechanics and Jones polynomials are drawn[ This allows a better insight into the nature of the proposed compacti_cation\ the associated E"# space and the Pisot!Vijayvaraghavan number 0:f23[125956866 representing it|s dimension[ This dimension is