Question

how to simplify 4cos^2 x ???? :(

Answer 1

uhm... can't be simplified any further

Answer 2

yes :P \[4 \left(\begin{matrix}1+\cos2x \\ 2\end{matrix}\right)\]

Answer 3

But I dont know how to arrive to this answer.. I dont know what to do!

Answer 4

that's not simplification. It's just a different but equivalent form

Answer 5

if you want to get rid of the power, i guess you could do \[\cos^2(x) = (1 + \cos^2(x))/2\]

Answer 6

its the power reduction formula for cos^2(x)

Answer 7

btw, that can be simplified to 2 + 2cos(2x)

Answer 8

but why the 2 is not an exposant anymore ??

Answer 9

that's wrong, its supposed to be\[\cos^2(x)=(1+\cos(2x))/2\]

Answer 10

its the power reduction formula

Answer 11

http://www.proofwiki.org/wiki/Power_Reduction_Formulas

Answer 12

Thanks youuuuu a lot :)!!