Over Lesson 9 2 B Graph the function

Over Lesson 9 -2 B. Graph the function r = 3 – 3 cos θ. A. C. B. D.

You used a polar coordinate system to graph points and equations. (Lessons 9 -1 and 9 -2) • Convert between polar and rectangular coordinates. • Convert between polar and rectangular equations.

Polar Coordinates to Rectangular Coordinates A. Find the rectangular coordinates for x = r cos Conversion formula . y = r sin = 2 cos r = 2 and = = 2 sin = Simplify. = =1 =

Polar Coordinates to Rectangular Coordinates The rectangular coordinates of D are approximately (1, 1. 73). Answer: or

Polar Coordinates to Rectangular Coordinates B. Find the rectangular coordinates for F(– 5, 45°). For F(– 5, 45°), r = – 5 and = 45°. x = r cos Conversion formula y = r sin = – 5 cos 45° r = – 5 and = 45° = – 5 sin 45° = Simplify. = = =

Polar Coordinates to Rectangular Coordinates The rectangular coordinates of F are approximately (– 3. 54, – 3. 54). Answer: or

Polar Coordinates to Rectangular Coordinates C. Find the rectangular coordinates for H(4, – 240°). For H(4, – 240°), r = 4 and = – 240°. x = r cos Conversion formula y = r sin = 4 cos (– 240°) r = 4 and = – 240° = 4 sin (– 240°) = = = – 2 Simplify. =

Polar Coordinates to Rectangular Coordinates The rectangular coordinates of H are approximately (– 2, 3. 46). Answer: or

Find the rectangular coordinates for R(– 8, 300°). A. B. C. D.

Rectangular Coordinates to Polar Coordinates A. Find two pairs of polar coordinates for the point E(2, – 4). For E(x, y) = (2, – 4), x = 2 and y = – 4. Because x > 0, use tan– 1 to find . Conversion formula x = 2 and y = – 4 Simplify. ≈ – 1. 11 or 5. 18

Rectangular Coordinates to Polar Coordinates One set of polar coordinates for E is (4. 47, – 1. 11). Another representation that uses a positive -value is (4. 47, – 1. 107 + 2π) or (4. 47, 5. 18), as shown. 5. 18 Answer:

Rectangular Coordinates to Polar Coordinates One set of polar coordinates for E is (4. 47, – 1. 11). Another representation that uses a positive -value is (4. 47, – 1. 107 + 2π) or (4. 47, 5. 18), as shown. 5. 18 Answer: Sample Answer: E(4. 47, – 1. 11) and E(4. 47, 5. 18)

Rectangular Coordinates to Polar Coordinates B. Find two pairs of polar coordinates for the point G(– 2, – 4). For G(x, y) = (– 2, – 4), x = – 2 and y = – 4. to find . Because x < 0, use Conversion formula x = – 2 and y = – 4

Rectangular Coordinates to Polar Coordinates Simplify. One set of polar coordinates for G is approximately (4. 47, 4. 25). Another representation that uses a negative r-value is (– 4. 47, 4. 25 + π) or (– 4. 47, 7. 39), as shown. Answer:

Rectangular Coordinates to Polar Coordinates Simplify. One set of polar coordinates for G is approximately (4. 47, 4. 25). Another representation that uses a negative r-value is (– 4. 47, 4. 25 + π) or (– 4. 47, 7. 39), as shown. Answer: G(4. 47, 4. 25) and G(– 4. 47, 7. 39)

Find two pairs of polar coordinates for F(– 5, – 6) with the given rectangular coordinates. A. F(7. 81, 0. 69) or F(– 7. 81, 3. 83) B. F(– 7. 81, 0. 69) or F(7. 81, 3. 83) C. F(7. 81, 0. 88) or F(– 7. 81, 4. 02) D. F(– 7. 81, 0. 88) or F(7. 81, 4. 02)

Conversion of Coordinates A. ROBOTICS Refer to the beginning of the lesson. Suppose the robot is facing due east and its sensor detects an object at (3, 280°). What are the rectangular coordinates that the robot will need to calculate? x = r cos Conversion formula y = r sin = 3 cos 280 o r = 3 and = 280 o = 3 sin 280 o ≈ 0. 52 Simplify. ≈ – 2. 95

Conversion of Coordinates The object is located at the rectangular coordinates (0. 52, – 2. 95). Answer:

Conversion of Coordinates The object is located at the rectangular coordinates (0. 52, – 2. 95). Answer: (0. 52, – 2. 95)

Conversion of Coordinates B. ROBOTICS Refer to the beginning of the lesson. If a previously detected object has rectangular coordinates of (4, 9), what are the distance and angle measure of the object relative to the front of the robot? Conversion formula x = 4 and y = 9

Conversion of Coordinates ≈ 9. 85 Simplify. ≈ 66. 0° The object is located at the polar coordinates (9. 85, 66. 0°). Answer:

Conversion of Coordinates ≈ 9. 85 Simplify. ≈ 66. 0° The object is located at the polar coordinates (9. 85, 66. 0°). Answer: (9. 85, 66. 0°)

HIDDEN TREASURE A crew is using radar to search for pirate treasure hidden under water. Suppose the boat is facing due east, and the radar gives the polar coordinates of the treasure as (8, 205 o). What are the rectangular coordinates for the hidden treasure? A. (– 2. 56, – 1. 20) B. (– 7. 25, – 3. 38) C. (– 7. 25, 1. 69) D. (2. 56, 1. 2)

Rectangular Equations to Polar Equations A. Identify the graph of (x + 2) 2 + y 2 = 4. Then write the equation in polar form. Support your answer by graphing the polar form of the equation. The graph of (x + 2)2 + y 2 = 4 is a circle with radius 2 centered at (– 2, 0). To find the polar form of this equation, replace x with r cos and y with r sin . Then simplify. (x + 2)2 + y 2 = 4 (r cos + 2)2 + (r sin )2 = 4 Original equation x = r cos and y = r sin

Rectangular Equations to Polar Equations r 2 cos 2 + 4 r cos + 4 + r 2 sin 2 = 4 r 2 cos 2 + 4 r cos + r 2 sin 2 = 0 r 2 cos 2 + r 2 sin 2 = – 4 r cos r 2(cos 2 + sin 2 ) = – 4 r cos r 2(1) = – 4 r cos r = – 4 cos Multiply. Subtract 4 from each side. Isolate the squared terms. Factor. Pythagorean Identity Divide each side by r.

Rectangular Equations to Polar Equations The graph of this polar equation is a circle with radius 2 centered at (– 2, 0). Answer:

Rectangular Equations to Polar Equations The graph of this polar equation is a circle with radius 2 centered at (– 2, 0). Answer: circle; r = – 4 cos

Rectangular Equations to Polar Equations B. Identify the graph of 2 xy = 4. Then write the equation in polar form. Support your answer by graphing the polar form of the equation. The graph of 2 xy = 4 is a hyperbola with the x- and y-axes as asymptotes. 2 xy = 4 Original equation 2(r cos )(r sin ) = 4 x = r cos and y = r sin 2 r 2 (cos )(sin )= 4 Multiply.

Rectangular Equations to Polar Equations Divide each side by 2(cos )(sin ) Double Angle Identity Reciprocal Identity The graph of the polar equation r 2 = 4 csc 2θ is a hyperbola with the x- and y-axes as the asymptotes.

Rectangular Equations to Polar Equations Answer:

Rectangular Equations to Polar Equations Answer: hyperbola; r 2 = csc 2

Identify the graph of x = y 2. Then write the equation in polar form. A. circle; r = sin 2 B. ellipse; r 2 = cos C. hyperbola; r = tan sin D. parabola; r = cot csc

Polar Equations to Rectangular Equations A. Write the equation in rectangular form and then identify its graph. Support your answer by graphing the polar form of the equation. Original equation Find the tangent of each side. tan = Multiply each side by x.

Polar Equations to Rectangular Equations The graph of the equation is a line through the origin with a slope of 1. Answer:

Polar Equations to Rectangular Equations The graph of the equation is a line through the origin with a slope of 1. Answer: line; y = x

Polar Equations to Rectangular Equations B. Write the equation r = 5 in rectangular form and then identify its graph. Support your answer by graphing the polar form of the equation. r =5 Original equation r 2 = 25 Square each side. x 2 + y 2 = 25 r 2 = x 2 + y 2 The graph of the rectangular equation is a circle with radius 5 centered at (0, 0).

Polar Equations to Rectangular Equations Answer:

Polar Equations to Rectangular Equations Answer: circle; x 2 + y 2 = 25

Polar Equations to Rectangular Equations C. Write the equation r = 2 sin θ in rectangular form and then identify its graph. Support your answer by graphing the polar form of the equation. r = 2 sin r 2 = 2 r sin x 2 + y 2 = 2 y x 2 + y 2 – 2 y= 0 Original equation Multiply each side by r. r 2 = x 2 + y 2 and y = r sin Subtract 2 y from each side. Because in standard form, x 2 + (y – 1)2 = 1, you can identify the graph of this equation as a circle with radius 1 centered at (0, 1).

Polar Equations to Rectangular Equations Answer:

Polar Equations to Rectangular Equations Answer: circle; x 2 + (y – 1)2 = 1

Write the equation r = 6 sin in rectangular form and then identify its graph. A. x 2 + (y – 3)2 = 9; circle B. ; ellipse C. ; hyperbola D. x 2 = 6 y; parabola