- #1

PsychonautQQ

- 784

- 11

## 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 ;-(