Question

How do you simplify `[1-cos(80°)] / [1+cos(80)]`?

Answer 1

tan^2 40

Explanation:

Use trig identities:
`1 - cos 2a = 2sin^2 a`
`1 + cos 2a = 2cos^2 a`
In this case:
`1 - cos 80 = 2sin^2 40`
`1 + cos 80 = 2cos^2 40`
Therefor,
`(1 - cos 80)/(1 + cos 80) = tan^2 40`