Question

How do you solve `sec^2 - 4secx = 0`?

Answer 1

`y = 1/cos^2 x - 4/cos x = (1 - 4cos x)/cos^2 x`

y = 0 -> (1 - 4cos x) = 0

`cos x = 1/4 --> x = +- 75.52` deg