Question

Find the solution of ;? Cos²x— Sin²x =0.5

Answer 1

`x = +- pi/6 + kpi`

Explanation:

Use trig identity: `cos^2 a - sin^2 a = cos 2a`.
In this case:
`cos^2 x - sin^2 x = cos 2x = 0.5`
Trig table and unit circle give 2 solutions:
cos 2x = 0.5 --> `2x = +- pi/3 + 2kpi`
`x = +- pi/6 + kpi`