Question

1+ cos^2x - (1-cos^2x) becomes 2 cos^2x. I thought it would equal 0. Is it because cos is an even function ???

Answer 1

1+cos^2x-(1-cos^2x)=1+cos^2x-1+cos^2x=2cos^2x
(-)*(-)=(+)

Answer 2

Does that help? @pitanje

Answer 3

so the second minus becomes positive and has nothing to do with being an odd function?

Answer 4

ya

Answer 5

when u multiply a minus with a minus u get positive

Answer 6

ok thanks

Answer 7

welcome:)