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10.5 Hyperbolas. p.615 What are the parts of a hyperbola? What are the standard form equations of a hyperbola? How do you know which way it opens? Given a & b, how do you find the value of c? How do you graph a hyperbola? Why does drawing a box make graphing easier?
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10.5 Hyperbolas p.615 What are the parts of a hyperbola? What are the standard form equations of a hyperbola? How do you know which way it opens? Given a & b, how do you find the value of c? How do you graph a hyperbola? Why does drawing a box make graphing easier? How do you write the equation from a graph?
Hyperbolas • Like an ellipse but instead of the sum of distances it is the difference • A hyperbola is the set of all points P such that the differences from P to two fixed points, called foci, is constant • The line thru the foci intersects the hyperbola @ two points (the vertices) • The line segment joining the vertices is the transverse axis, and it’s midpoint is the center of the hyperbola. • Has 2 branches and 2 asymptotes • The asymptotes contain the diagonals of a rectangle centered at the hyperbolas center
Asymptotes (0,b) Vertex (a,0) Vertex (-a,0) Focus Focus (0,-b) This is an example of a horizontal transverse axis (a, the biggest number, is under the x2 term with the minus before the y)
Standard Form of Hyperbola w/ center @ origin Foci lie on transverse axis, c units from the center c2 = a2+b2
Graph 4x2 – 9y2 = 36 • Write in standard form (divide through by 36) • a=3 b=2 – because x2 term is ‘+’ transverse axis is horizontal & vertices are (-3,0) & (3,0) • Draw a rectangle centered at the origin. • Draw asymptotes. • Draw hyperbola.
Write the equation of a hyperbole with foci (0,-3) & (0,3) and vertices (0,-2) & (0,2). • Vertical because foci & vertices lie on the y-axis • Center @ origin because focus & vertices are equidistant from the origin • Since c=3 & a=2, c2 = b2 + a2 • 9 = b2 + 4 • 5 = b2 • +/-√5 = b
What are the parts of a hyperbola? Vertices, foci, center, transverse axis & asymptotes • What are the standard form equations of a hyperbola? • How do you know which way it opens? Transverse axis is always over a • Given a & b, how do you find the value of c? c2 = a2 + b2 • How do you graph a hyperbola? Plot a and b, draw a box with diagonals. Draw the hyperbola following the diagonals through the vertices.
Why does drawing a box make graphing easier? The diagonals of the box are the asymptotes of the hyperbola. • How do you write the equation from a graph? Identify the transverse axis, find the value of a and b (may have to use c2 = a2 + b2) and substitute into the equation.
Assignment Page 619, 15-18, 19-39 odd, 57-61 odd, skip 37
10.5 Hyperbolas, day 2 What are the standard form equations of a hyperbola if the center has been translated?
Write the equation of the hyperbola in standard form. 16y2 −36x2 + 9 = 0 16y2 −36x2 = −9
Translated Hyperbolas In the following equations the point (h,k) is the center of the hyperbola. Horizontal axis Vertical axis Remember c2 = a2 + b2
Write an equation for the hyperbola. Vertices at (5, −4) and (5,4) and foci at (5,−6) and (5,6). Draw a quick graph. Equation will be:
(5,6) (5,4) Center (0,5) (h,k) a = 4, c = 6 c2 = a2 + b2 62 = 42 + b2 36 = 16 + b2 20 = b2 Center? (5,−4) (5,−6)
Graphing the Equation of a Translated Hyperbola (x + 1)2 Graph (y + 1)2– = 1. 4 (–1, 0) (–1, –1) (–1, –2) SOLUTION The y2-term is positive, so thetransverse axis is vertical. Sincea2 = 1 and b2 = 4, you know thata = 1 and b = 2. Plot the center at (h, k) = (–1, –1). Plot the vertices 1 unit above and below the center at (–1, 0) and (–1, –2). Draw a rectangle that is centered at (–1, –1) and is 2a = 2 units high and 2b = 4 units wide.
Graphing the Equation of a Translated Hyperbola (x + 1)2 Graph (y + 1)2– = 1. 4 (–1, 0) (–1, –1) (–1, –2) SOLUTION The y2-term is positive, so thetransverse axis is vertical. Sincea2 = 1 and b2 = 4, you know thata = 1 and b = 2. Draw the asymptotes through the corners of the rectangle. Draw the hyperbola so that it passes through the vertices and approaches the asymptotes.
What are the standard form equations of a hyperbola if the center has been translated?
Assignment Page 618, 20-38 even. 50-58 even Page 628, 19-20, 23, 26