Question

sec(15[pi])/(8)

Answer 1

15[pi])/(8) radians = 337.5 degrees
or -22.5 degrees

15[pi])/(8
= sec 337.5 dgs
= sec (-22.5) dgs
= sec 22.5 dgs

= 1/cos 22.5 dgs

so let's find cos 22.5
cos 2A = 2cos^2 A - 1
cos 45 = 2cos^2 22.5 - 1
(√2/2 + 1)/2 = cos^2 22.5
(√2 + 2)/4 = cos^2 22.5
cos 22.5 = √(√2+2)/2

sec 22.5 = 2/√(√2+2)

sec(15[pi])/(8) = 2/√(√2+2)