Question

Question #24c34

Answer 1

Prove trig identity.

Explanation:

`cos ^4 t - sin^4 t = (cos^2 t - sin^2 t)(cos^2 t + sin^2 t).`
Reminder:
`cos^2 t - sin^2 t = cos 2t = 1 - 2sin^2 t`
`cos^2 t + sin^2 t = 1`.
There for:
`cos^4 t - sin^4 t = 1 - 2sin^2 t`