17 4o A Tangent Lines and Normal Lines In Exercises 57 and St find equations for the tangent line and normal line to the circh at each given point. (The normal line at a point is perpendicule to the tangent line at the point.) Use a graphing utility to grap Differentiation 150 Chapter 2 42. Каppa curve 41. Lemniscate HOW DO YOU SEE IT? Use the graph to 70. yx2+y2) = 2r? 3(2+y2) = 100(2-y) the circle, the tangent lines, and the normal lines. 58. x2y2 36 (6, 0), (5, VI1) answer the questions. y3-9y2 + 27y+5x? = 47 3 57. x2+y2 = 25 (4, 3), (-3, 4) 6 2T(1,1) (4, 2) 2 59. Normal Lines Show that the normal line at any point o the circle x2 +y2 = r2 passes through the origin 60. Circles Two circles of radius 4 are tangent to the graph of y2 = 4x at the point (1, 2). Find equations of these two circle Vertical and Horizontal Tangent Lines In Exercises 61 and 62, find the points at which the graph of the equation has x 2 3 -2 -3t 2 (a) Which is greater, the slope of the tangent line at x =-3 or the slope of the tangent line at EXPLORING CONCEPTS 43. Implicit and Explicit Forms Write two different equations in implicit form that you can write in explicit form. Then write two different equations in implicit form that you cannot write in explicit form. A x=I1? A (b) Estimate the point(s) where the graph has a vertical tangent line. a vertical or horizontal tangent line. A A 61.25x2 16y2 + 200x 160y +400 = 0 (c) Estimate the point(s) where the graph has a horizontal tangent line. 0 44. Think About It Explain why the derivative of x2 y22= 1 does not mean 62. 4x2+y2- 8x +4y +4 anything. AOrthogonal Trajectories In Exercises 63-66 graphing utility to sketch the intersecting graphs of the equations and show that they are orthogonal. [Two graphs are orthogonal if at their point(s) of intersection, their tangent perpendicular to each other.] 71. Finding Equations of Tangent Lines Consider equation x4 4(4x2 - y2). (a) Use a graphing utility to graph the equation. 45. Ellipse (a) Use implicit differentiation to find an equation of the are (b) Find and graph the four tangent lines to the curve y = 3. (c) Find the exact coordinates of the point of intersecti the two tangent lines in the first quadrant. = 1 at (1, 2). 8 tangent line to the ellipse 2 64. y2 x3 63. 2x2+y2 6 (b) Show that the equation of the tangent line to the ellipse 2x2 +3y2 5 y2 4x x2 y2 + УoУ Xx (Yo Yo) is a2 = 1. 66. x3 = 3(y - 1) = 1 at 65. x + y = 0 a2 b2 72. Tangent Lines and Intercepts Let L be any ta x(3y 29) 3 = sin y 46. Hyperbola line to the curve (a) Use implicit differentiation to find an equation of the AOrthogonal Trajectories In Exercises 67 and 68, verit that the two families of crves are orthogonal, where C and K are real numbers. Use raphing utility to graph the two families for two values ofsod two values of K. 1 at (3, -2). tangent line to the hyperbola 6 Show that the sum of the x- and y-intercepts of L is c. (b) Show that the equation of the tangent line to the hyperbola x2y2 a2 y) isoXYoy a2 b2 1 at (x 1. 67. xy = C, x2- y2 - 68. x2 +y2 = C2, y= E b2 SETH N PROJECT Determining a Differentiable Function In Exercises 47 and 48, find dy/dx implicitly and find the largest interval of the form -a