Posted by Paul on .
Evaluate the following integral
integral 1 = a and b = 4 of
sinx dx/(1+cos)^2
u = cosx
du = sinx dx
so from here I don't know if I can do:
1 du = sinx dx
or 1/sin du = x dx

Calculus 
Damon,
u = 1 + cos x
du = sin x dx
so we have
du/u 
Calculus 
Paul,
so I tried again and I got this, don't know if it's good:(I also put the wrong a and b)
integral 0 = a and b = pi/3 of
sinx dx/(1+cos)^2
u = cosx
du= sinxdx
1 du = sinx dx
so: integral 1 du/(1+u)^2
= 1/(u+1)
if x = 0, then u = 1
if x = pi/3, then u = 1
so 1/1+1  1/1+1 = 0
Is this correct? 
I mean 
Damon,
du/(u)^2

Calculus 
Damon,
du/u^2 > 1/u + c

Calculus 
Paul,
ok Damon, so if you integrate what you have me, you get 1/u no? Because 1/u^2 = 1/u, so 1/u^2 = 1/u?

Calculus 
Damon,
so
1/(1+cos x) + c 
Calculus 
Damon,
Yes, you have it.

Calculus 
Paul,
awesome, thanks man!

Calculus 
Damon,
You are welcome.