Math help?

Question

Use the half-angle formulas to find the exact value of each trigonometric fuction
sec (15pi/8)

Answer 1

Frozen water, but to be snow it has to be frozen in the cloud. Hail has to melt and freeze over and over again, and sleet is water that has fallen from the cloud but then the air is freezing temp so it freezes it, its therefore sleet.

Answer 2

sec x = 1/cos x
Use the half-angle formula for the cosine.

sec x = 1/cos x = 1/sqrt{[(cos 2x) + 1] / 2}
= sqrt{2 / [(cos 2x) + 1}

So

sec 15pi/8 = sqrt{2 / [(cos 15pi/4) + 1}
= sqrt(2 / [1/2^.5 +1] = sqrt{4 - 2^.5}

Answer 3

i know that, look at the answer sheet