Question

cos^(2)x(1+tan^(2)x)=1

please help prove this

Answer 1

(1-cosx)(1+cosx)=sin^(2)x ??

Answer 2

\[\cos ^{2}x + \cos ^{2}x(\sin ^{2}x)/\cos ^{2} x\]

we have multiplied the cos^2 x thru and tan ^2x = sin^2x/cos^2x

cancelling the cos^2x 's out that leaves the magic identity:
sin^2x + cos^2x = 1

Answer 3

ohh i see !!! Thanks !! How would you do the bottom one?

Answer 4

@Loser66 do you know how to do this?
1-cosx)(1+cosx)=sin^(2)x

Answer 5

(a+b)(a-b)= a^2-b^2
yours is (1-cos)(1+cos) = 1-cos^2 =sin^2 , quite clear, right?

Answer 6

lost

Answer 7

why? a is 1
b is cos

Answer 8

so im going to use the Pythagorean therom?