- #1
PsychonautQQ
- 784
- 10
Homework Statement
Find the area inside r = 9sinθ but outside r = 2
Homework Equations
Area = 1/2(Integral of (f(θ)^2 - g(θ)^2)dθ
The Attempt at a Solution
f(θ)^2 =
81sin^2θ = 81((1-cos(2θ))/2)
g(θ)^2 = 4
f(θ)^2 - g(θ)^2 = 36.5 - cos(2θ)/2
integral of (36.5 - cos(2θ)/2)
[36.5θ - sin(2θ)/4]
Area = 1/2[36.5θ - sin(2θ)/4]
If I integrate from 0 to ∏/2 then multiply that area times two I get 114.6681319
Which is the wrong answer.
Where did I go wrong ;-(