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## Homework Statement

tan^2x - sin^2x = sin^2x*tan^2x

## Homework Equations

## The Attempt at a Solution

This is how my teacher solved it.

Sin^2x sin^2x

______ - ______

Cos^2x 1

sin^2x - cos^2x*sin^2x

_________________________

cos^2x

= sin^2x (1-cos^2x)

___________________

cos^2x

=sin^2x *sin^2x

______________

cos^2x

thus giving the answer. I dont understand what happends on the third line. How can 1-cos^2x be bracketed if cos^2x*sin^2x are one term, even though they equal one, how can that equal 1-cos^2x?