Solve Sec(2x)-4=0 for the first two positive solutions. thanks!

sec(2x) - 4 = 0

sec(2x) = 4

1 / cos(2x) = 4

cos(2x) = 1/4

2x = cos⁻¹(1/4) + 2nπ   or   2x = -cos⁻¹(1/4) + 2nπ

(where n is any integer)

x = 1/2 cos⁻¹(1/4) + nπ   or   x = -1/2 cos⁻¹(1/4) + nπ

The first two positive solutions occur for n = 0 in the first family of solutions, and for n = 1 in the second family, so

x = 1/2 cos⁻¹(1/4)   or   x = π - 1/2 cos⁻¹(1/4)

x ≈ 0.659   or   x ≈ 2.483

40 is the final : )