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Quadric Surfaces the University of Kansas 1 / 23 2 2 2 � X  � Y  Ellipse of Semi-Major, Semi-Minor Axes A, B: a + B = 1 1 circle of radius r: x 2 + y 2 = r 2 2 2 2 x y ellipse of semi-major, semi-minor axes a; b: a + b = 1 2 2 3 x y hyperbola of semi-major, semi-minor axes a; b: a − b = 1 4 parabola: y = ax 2 Considering these conic sections as three-dimensional objects by letting z vary, we obtain the family of cylinders. Conic Sections Recall the usual conic sections from the Cartesian plane. MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 1 / 23 2 2 2 x y ellipse of semi-major, semi-minor axes a; b: a + b = 1 2 2 3 x y hyperbola of semi-major, semi-minor axes a; b: a − b = 1 4 parabola: y = ax 2 Considering these conic sections as three-dimensional objects by letting z vary, we obtain the family of cylinders. Conic Sections Recall the usual conic sections from the Cartesian plane. 1 circle of radius r: x 2 + y 2 = r 2 MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 1 / 23 2 2 3 x y hyperbola of semi-major, semi-minor axes a; b: a − b = 1 4 parabola: y = ax 2 Considering these conic sections as three-dimensional objects by letting z vary, we obtain the family of cylinders. Conic Sections Recall the usual conic sections from the Cartesian plane. 1 circle of radius r: x 2 + y 2 = r 2 2 2 2 x y ellipse of semi-major, semi-minor axes a; b: a + b = 1 MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 1 / 23 4 parabola: y = ax 2 Considering these conic sections as three-dimensional objects by letting z vary, we obtain the family of cylinders. Conic Sections Recall the usual conic sections from the Cartesian plane. 1 circle of radius r: x 2 + y 2 = r 2 2 2 2 x y ellipse of semi-major, semi-minor axes a; b: a + b = 1 2 2 3 x y hyperbola of semi-major, semi-minor axes a; b: a − b = 1 MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 1 / 23 Considering these conic sections as three-dimensional objects by letting z vary, we obtain the family of cylinders. Conic Sections Recall the usual conic sections from the Cartesian plane. 1 circle of radius r: x 2 + y 2 = r 2 2 2 2 x y ellipse of semi-major, semi-minor axes a; b: a + b = 1 2 2 3 x y hyperbola of semi-major, semi-minor axes a; b: a − b = 1 4 parabola: y = ax 2 MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 1 / 23 Conic Sections Recall the usual conic sections from the Cartesian plane. 1 circle of radius r: x 2 + y 2 = r 2 2 2 2 x y ellipse of semi-major, semi-minor axes a; b: a + b = 1 2 2 3 x y hyperbola of semi-major, semi-minor axes a; b: a − b = 1 4 parabola: y = ax 2 Considering these conic sections as three-dimensional objects by letting z vary, we obtain the family of cylinders. MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 1 / 23 Cylinders MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 2 / 23 Cylinders MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 3 / 23 Cylinders MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 4 / 23 Cylinders MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 5 / 23 Quadric surfaces are defined by quadratic equations, e.g., Ax2 + By 2 + Cz2 + Dxy + Eyz + Fxz + ax + by + cz + d = 0: Given that D = E = F = 0; we say that a quadric surface is in standard position or of standard form. Quadric surfaces are uniquely determined by their traces, i.e., the conic sections that are obtained by intersecting a quadric surface with a plane that is parallel to one of the three coordinate planes. Basics of Quadric Surfaces Quadric surfaces are three-dimensional generalizations of the conic sections of the (two-dimensional) Cartesian plane. MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 6 / 23 Given that D = E = F = 0; we say that a quadric surface is in standard position or of standard form. Quadric surfaces are uniquely determined by their traces, i.e., the conic sections that are obtained by intersecting a quadric surface with a plane that is parallel to one of the three coordinate planes. Basics of Quadric Surfaces Quadric surfaces are three-dimensional generalizations of the conic sections of the (two-dimensional) Cartesian plane. Quadric surfaces are defined by quadratic equations, e.g., Ax2 + By 2 + Cz2 + Dxy + Eyz + Fxz + ax + by + cz + d = 0: MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 6 / 23 Quadric surfaces are uniquely determined by their traces, i.e., the conic sections that are obtained by intersecting a quadric surface with a plane that is parallel to one of the three coordinate planes. Basics of Quadric Surfaces Quadric surfaces are three-dimensional generalizations of the conic sections of the (two-dimensional) Cartesian plane. Quadric surfaces are defined by quadratic equations, e.g., Ax2 + By 2 + Cz2 + Dxy + Eyz + Fxz + ax + by + cz + d = 0: Given that D = E = F = 0; we say that a quadric surface is in standard position or of standard form. MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 6 / 23 Basics of Quadric Surfaces Quadric surfaces are three-dimensional generalizations of the conic sections of the (two-dimensional) Cartesian plane. Quadric surfaces are defined by quadratic equations, e.g., Ax2 + By 2 + Cz2 + Dxy + Eyz + Fxz + ax + by + cz + d = 0: Given that D = E = F = 0; we say that a quadric surface is in standard position or of standard form. Quadric surfaces are uniquely determined by their traces, i.e., the conic sections that are obtained by intersecting a quadric surface with a plane that is parallel to one of the three coordinate planes. MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 6 / 23 We can describe an ellipsoid in standard position by an equation x 2 y 2 z 2 + + = 1: a b c Given that a = b = c = r; we obtain the ellipsoid x2 + y 2 + z2 = r 2; i.e., a sphere centered at the origin (0; 0; 0) with radius r > 0: Common Examples of Quadric Surfaces Ellipsoids are quadric surfaces whose traces are ellipses. MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 7 / 23 Common Examples of Quadric Surfaces Ellipsoids are quadric surfaces whose traces are ellipses. We can describe an ellipsoid in standard position by an equation x 2 y 2 z 2 + + = 1: a b c Given that a = b = c = r; we obtain the ellipsoid x2 + y 2 + z2 = r 2; i.e., a sphere centered at the origin (0; 0; 0) with radius r > 0: MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 7 / 23 Common Examples of Quadric Surfaces MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 8 / 23 We can describe a hyperboloid in standard position by an equation x 2 y 2 z 2 + = + 1 (1) a b c x 2 y 2 z 2 or + = − 1: (2) a b c Observe that the figure described by equation (2) does not contain any points such that the z-coordinate satisfies −c < z < c; otherwise, the right-hand side would be negative while the left-hand side is positive by definition | a contradiction. Consequently, the hyperboloid of equation (2) is said to have two \sheets." Common Examples of Quadric Surfaces Hyperboloids are quadric surfaces whose xy-traces are ellipses and whose yz- and xz-traces are hyperbolas. MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 9 / 23 Observe that the figure described by equation (2) does not contain any points such that the z-coordinate satisfies −c < z < c; otherwise, the right-hand side would be negative while the left-hand side is positive by definition | a contradiction. Consequently, the hyperboloid of equation (2) is said to have two \sheets." Common Examples of Quadric Surfaces Hyperboloids are quadric surfaces whose xy-traces are ellipses and whose yz- and xz-traces are hyperbolas. We can describe a hyperboloid in standard position by an equation x 2 y 2 z 2 + = + 1 (1) a b c x 2 y 2 z 2 or + = − 1: (2) a b c MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 9 / 23 otherwise, the right-hand side would be negative while the left-hand side is positive by definition | a contradiction. Consequently, the hyperboloid of equation (2) is said to have two \sheets." Common Examples of Quadric Surfaces Hyperboloids are quadric surfaces whose xy-traces are ellipses and whose yz- and xz-traces are hyperbolas. We can describe a hyperboloid in standard position by an equation x 2 y 2 z 2 + = + 1 (1) a b c x 2 y 2 z 2 or + = − 1: (2) a b c Observe that the figure described by equation (2) does not contain any points such that the z-coordinate satisfies −c < z < c; MATH 127 (Section 12.6) Quadric Surfaces The University of Kansas 9 / 23 Consequently, the hyperboloid of equation (2) is said to have two \sheets." Common Examples of Quadric Surfaces Hyperboloids are quadric surfaces whose xy-traces are ellipses and whose yz- and xz-traces are hyperbolas.
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