- #1
n77ler
- 89
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Homework Statement
int sqrt 8x-x^2
Homework Equations
trig sub
The Attempt at a Solution
complete the square
integral becomes
int sqrt 16-(x-4)^2
let x-4= 16sin(Q) sqrt 16-(x-4)^2 =sqrt 16-256sin^2(Q)
dx= 16cos(Q)dQ = 16cos(Q)
int 16cos(Q)16cos(Q) dQ=256 int cos^2(Q)dQ double angle formula
128 int 1+cos(2Q) dQ let u=2Q 1/2du=dQ
This is the part where i get messed up...
128 int 1 dQ + 128 int cos(u)du
So the first part is just 128Q and the integral of 128intcos(u)du is 128sin(u)
So do I fill 2Q back in for u? Then if I fill it back in do I use Q=[sqrt16-(x-4)^2] / 16 ??