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Geometry and Mensuration IV.7 11 Geometry and Mensuration

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Geometry and Mensuration IV.7 11 Geometry and Mensuration The chapters on geometry and mensuration have their own The following is a comprehensive collection of formulae share of questions in the CAT and other MBA entrance ex- based on two-dimensional figures. The student is advised aminations. For doing well in questions based on this chapter, to remember the formulae in this chapter so that he is able the student should familiarise himself/herself with the to solve all the questions based on this chapter. basic formulae and visualisations of the various shapes of solids and two-dimensional figures based on this chapter. THEORY The following is a comprehensive collection of for- mulae based on two-dimensional and three-dimensional Basic Conversions figures: For the purpose of this chapter we have divided the A. 1 m = 100 cm = 1000 mm B. 1 m = 39.37 inches theory in two parts: 1 km = 1000 m 1 mile = 1760 yd ∑ Part I consists of geometry and mensuration of two- = 5/8 miles = 5280 ft dimensional figures 1 inch = 2.54 cm 1 nautical mile (knot) ∑ Part II consists of mensuration of three-dimensional = 6080 ft figures. C. 100 kg = 1 quintal D. 1 litre = 1000 cc 10 quintal = 1 tonne 1 acre = 100 sq m = 1000 kg PART I: GEOMETRY 1 kg = 2.2 pounds 1 hectare = 10000 sq m (approx.) INTRODUCTION TYPES OF ANGLES Geometry and Mensuration are important areas in the CAT examination. In the Online CAT, the Quantitative Aptitude Basic Definitions section has consisted of an average of 15–20% questions from these chapters. Besides, questions from these chapters Acute angle: An angle whose measure is less than 90 appear prominently in all major aptitude based exams for degrees. The following is an acute angle. MBAs, Bank POs, etc. Hence, the student is advised to ensure that he/she studies this chapter completely and thoroughly. Skills to be developed while studying and practising this chapter will be based on the application of formula and visualisation of figures and solids. The principal skill required for doing well in this chapter is the ability to apply the formulae and theorems. PDF DROWNLOAD FROM: SARKARIPOST.IN IV.8 How to Prepare for Quantitative Aptitude for CAT Right angle: An angle whose measure is 90 degrees. The not need to be adjacent to be called supplementary (quite following is a right angle. like complementary angles). The only condition for two angles to be called supplementary is if they are adding up to 180 degrees. 2 1 Vertical angles: Angles that have a common vertex and whose sides are formed by the same lines. The follow- ∠ ∠ Obtuse angle: An angle whose measure is bigger than 90 ing( 1 and 2) are vertical angles. degrees but less than 180 degrees. Thus, it is between 90 degrees and 180 degrees. The following is an obtuse angle. 1 2 Angles formed when two parallel lines, are crossed by a transversal: When two parallel lines are crossed by a third line, (transversal), 8 angles are formed. Take a look Straight angle: Is an angle whose measure is 180 degrees. at the following figure: Reflex angle: An angle whose measure is more than 12 180 degrees but less than 360 degrees. The following is 85 a reflex angle. 43 67 Adjacent angles: Angles with a common vertex and one common side. In the figure below, ∠1 and ∠2 are adjacent angles. Angles 3,4,5,8 are interior angles. Angles 1,2,6,7 are exterior angles. Alternate interior angles: Pairs of interior angles on 21 opposite sides of the transversal. For instance, angle 3 and angle 5 are alternate interior angles. Angle 4 and angle 8 are also alternate interior Complementary angles: Two angles whose measures angles. Both the angles in a pair of alternate interior angles add to 90 degrees ∠1 and ∠2 are complementary angles are equal. Hence, in the figure we have: Angle 3 = Angle because together they form a right angle. 5; Also Angle 4 = Angle 8. However, one thing that you should note is that, even Alternate exterior angles: Pairs of exterior angles on though in the figure given here, the two angles are shown as opposite sides of the transversal. adjacent, they need not be so to be called complementary. As Angle 2 and angle 7 are alternate exterior angles. Angles long as two angles add up to 90 degrees, they would be called 1 and 6 are also alternate exterior angles. Both the angles complementary (even if they are not adjacent to each other). in a pair of alternate exterior angles are equal. Thus, in the figure Angle 2 = Angle 7 and Angle 1 = Angle 6. Co-interior angles: When two lines are cut by a third line (transversal) co-interior angles are between the pair of lines on the same side of the transversal. If the lines that 2 1 are being cut by the transversal are parallel to each other, the co-interior angles are supplementary (add up to 180 degrees). In the given figure, angles 3 and 8 are co-interior Supplementary angles: Two angles whose measures add angles. Also, angles 4 and 5 are co-interior angles, since, ∠ ∠ up to 180 degrees. The following angles 1 and 2 are the lines being cut are parallel in this case, ∠3 + ∠8 = supplementary angles. However, supplementary angles do 180. Also, ∠4 + ∠5 = 180. PDF DROWNLOAD FROM: SARKARIPOST.IN Geometry and Mensuration IV.9 Corresponding angles: Are pairs of angles that are in X similar positions when two parallel lines are intersected by a transversal. Angle 3 and angle 2 are corresponding angles. Y Similarly, the pairs of angles, 1 and 4; 5 and 7; 6 and 8 are corresponding angles. Corresponding angles are equal. Thus, in the figure- ∠1 = ∠4; ∠5 = ∠7; ∠2 = ∠3 & ∠6 O Z = ∠8. Linear pair: ∠XOY and ∠YOZ are linear pair angles. One The disance between the lines OX & OY and the lines side must be common (e.g. OY)and these two angles must OY & OZ are equal to each other. be supplementary. Y PRACTICE EXERCISE 1. What is the value of x in the given figure? 1 2 R XO Z ∠ ∠ ∠ ° 7x Angles on the side of a line: 1 + 2 + 3 = 180 3x PO Q o o (a) 18 (b) 20 o 2 (c) 28 (d) None of these 2. In the given figure, find the value ofa ( + b) 1 3 Angles around the point: ∠1 + ∠2 + ∠3 + ∠4 + ∠5 = 360° 90° 5b 2a 3a 2 (a) 50o (b) 54o (c) 60o (d) None of these 1 3 3. If 2a + 3, 3a + 2 are complementary, then a = ? o o 45 (a) 17 (b) 20 (c) 23o (d) 26o 4. If 5x + 17o and x + 13o are supplementary, then x = ? (a) 20o (b) 25o (c) 30o (d) None of these Angle Bisector: OY is the angle bisector for the ∠XOZ. 5. An angle is exactly half of its complementary angle, 1 i.e., ∠XOY = ∠ZOY = ∠XOZ then find the angle. 2 (a) 30o (b) 40o X (c) 50o (d) 60o 6. In the following figure, lines L1 and L2 are parallel to each other. Find the value of q. Y L1 45° r q O Z When a line segment divides an angle equally into two parts, then it is said to be the angle bisector (OY). p° 125° L2 (Angle bisector is equidistant from the two sides of the o o angle.) (a) 60 (b) 80 (c) 90o (d) 85o PDF DROWNLOAD FROM: SARKARIPOST.IN IV.10 How to Prepare for Quantitative Aptitude for CAT o o 7. In the given figure if L1||L2 then values of x, y, z are: (a) 40 (b) 60 o o (c) 70 (d) 80 L1 46° x 13. If AB||CD and AF||BE then the value of x is: 20° F y z 62° B D L2 x (a) 98o, 98o,36o (b) 98o, 36o, 98o 108° (c) 36o,98o,36o (d) None of these A E 8. In the given diagram if BC||ED and ∠BAC = 70°, then find the value of d and c. C A (a) 108o (b) 72o 70 (c) 88o (d) 82o 14. In the figure if PQ||SR and ST||QR then x = ? d e D E PST 128 b c B C 40° x (a) 52o, 58o (b) 58o, 52o (c) 44o, 36o (d) 36o, 44o 9. In the given diagram if AB||CD and ∠ABO = 60° 60° and ∠BOC = 110°, find ∠OCD QR A B (a) 70o (b) 80o (c) 90o (d) 100o O 15. In the given figure, if AB||CD then the value of x =? D C AC (a) 40o (b) 50o (c) 60o (d) 70o 10. In the figure given, two parallel lines are intersected by a transversal. Then, find the value of x. 120° x° B D 3x + 10° 35° x + 10° E o o (a) 40 (b) 50 o o (c) 55o (d) 65o (a) 135 (b) 145 (c) 155o (d) None of these 11. Maximum number of points of intersection of five lines on a plane is 16. If PQ||RS and QT||SU then find the value of x + y (a) 6 (b) 8 W (c) 10 (d) 12 12. If PQ||RS then find the value of x. T P R 42° P Q 80° U y U T Q 40° X x° 68° R S S PDF DROWNLOAD FROM: SARKARIPOST.IN Geometry and Mensuration IV.11 o o (a) 188 (b) 202 o o ANSWER KEY (c) 208 (d) 212 17.
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