Hyperbolas 4.4 Chapter 10 – Conics
Yesterday’s Exit Slip Find the coordinates of the center of the graph. 1. 2. 3. 4. A. (–1, –1) B. (0, 0) C. (1, 0) D. (2, 1) Find the coordinates of the foci of the graph. A. (1, 1), (–1, 1) B. (2, 1), (–2, 1) C. (2, 0), (–2, 0) D. Find the length of the major axis of the graph. A. 8 B. 10 C. 12 D. 14 Find the length of the minor axis of the graph. A. 8 B. 6 C. 4 D. 2
Yesterday’s Exit Slip Graph the ellipse 5. A. B. C. D.
You graphed and analyzed equations of ellipses. (Lesson 10–4) Write equations of hyperbolas. Graph hyperbolas.
Hyperbolas
Graph of a Hyperbola hyperbola transverse axis conjugate axis foci vertices co-vertices constant difference
Writing the Equation of a Hyperbola Write an equation for the hyperbola shown. The center is the midpoint of the segment connecting the vertices, or (0, 0). The value of a is the distance from the center to a vertex, or 2 units. The value of c is the distance from the center to a focus, or 4 units. Find b: c2 = a2 + b2 The transverse axis is vertical → the y comes first when we write the equation 42 = 22 +b2 16 = 4 + b2 12 = b2
Example 1 What is an equation for the hyperbola? A. B. C. D.
Graphing Hyperbolas Identify the vertices, foci, and asymptotes. Step 1 Find the center. The center is at (3, –5). Step 2 Find a, b, and c. From the equation a2 = 4, so a = 2 and b2 = 9, so b = 3. c2 = a2 + b c2 = 4 + 9 c2 = 13 c = or about 3.61
Step 3 Identify the vertices and foci. The hyperbola is horizontal (x comes first in the equation) The vertices are 2 units from the center (given by knowing a) So the vertices are at (1, –5) and (5, –5). The foci are about 3.61 units from the center. The foci are at (6.61, –5) and (–0.61, –5). Step 4 Identify the asymptotes. Equation for the asymptote of a horizontal hyperbola a = 2, b = 3, h = 3, and k = –5 The equations for the asymptotes are
Step 5 Graph the hyperbola. Plot the points for the center, vertices, and foci Use the value for a and b to draw a box Graph the asymptotes by drawing in the diagonals of the box Draw symmetrical curves using the asymptotes as your guide
Example 2 Identify the asymptotes of the function A. B. C. D.