1. Today in Precalculus Go over homework Need a calculator
Notes: Converting between Polar and Rectangular Coordinates (there is a handout)
Homework

2. Example: Convert the following to rectangular coordinates (-2, 60°) b.
Polar coordinates can be converted to Cartesian (rectangular) coordinates by letting the pole be the origin and the polar axis the positive x-axis.
x = rcosθ
y = rsinθ
Example: Convert the following to rectangular coordinates
(-2, 60°) b. y x θ r
P(r, θ)

3. To convert from rectangular to polar coordinates: r2 = x2 + y2
tanθ = y/x
so θ = tan-1(y/x) y x θ r
(x,y)

4. Example: Convert the following to polar coordinates for the given interval: (-2, 2) for 2π ≤ θ ≤ 4π
Not in the correct quadrant so add π
π = 2.356
Not in the interval so add 2π

5. Example: Convert the following to polar coordinates for the given interval: (3, -5) for 0 ≤ θ ≤2π
but not in the interval so add 2π,
θ = 5.253
If asked to find all of its polar coordinates:

6. Practice Convert the following to rectangular coordinates 1.
2. (-1, 315°)

7. Practice Convert the following to polar coordinates (find all)
1. (1, 1)
2. (-2, 5)

8. Homework
Pg. 539: 1,3,15,19-27odd