Question

Simplify the expression cos(2*(arctan(x))
Really having trouble trying to simplify this thing. Would someone mind helping me out here?

Answer 1

do you mean write as algebraic expression?

Answer 2

No it just says to simplify this expression

Answer 3

so what does that mean?

Answer 4

arctanx=y
tany=x
required = cos(2y) = 2(cosy)^2-1
\[=2/((1+x ^{2}))-1 = (1-x ^{2})/(1+x ^{2})\]

Answer 5

I am lost at the third line.

Answer 6

So you basically disguise the arctan expression as a variable, and then go about with the simpliciation. ?

Answer 7

i can write this as algebraic expression but no one is telling me what simplify means here so i don't know exactly what you want but this is what i did

Answer 8

yes