Re: Trigonometric Integrals

Don't you understand that this is not a question of "Calculus" but of "Algebra"? $\displaystyle sin(x)(1- cos^2(x))(cos(x))= sin(x)(cos(x)- cos^3(x))= sin(x)cos(x)- sin(x)cos^3(x)$.

I have used the "distributive law", a(b+ c)= ab+ ac, twice.

Re: Trigonometric Integrals

You're just expanding - I am not quite up to scratch with the LateX so....

Int(75 s(1-c^2)c^2) = Int(75 sc^2 - sc^4) = Int(75 sc^2) - **Int(sc^4)**

The part that with the ? is the part that I bolded

Re: Trigonometric Integrals

I guess I didn't realize that $\displaystyle \int u-v=\int u - \int v$

Thank you both

Re: Trigonometric Integrals

$\displaystyle \int 75cos^2 x sin x dx - \int 75sin x cos^4 x$