SOLUTION: Determine all solutions of the equation in radians find cosx/2, given that sec x = 4 and x terminates in 0<x<pi/2. I tried and got +- sqr(5/8) but i don't how to make it to rad

Algebra ->  Trigonometry-basics -> SOLUTION: Determine all solutions of the equation in radians find cosx/2, given that sec x = 4 and x terminates in 0<x<pi/2. I tried and got +- sqr(5/8) but i don't how to make it to rad      Log On


   

Question 923529: Determine all solutions of the equation in radians
find cosx/2, given that sec x = 4 and x terminates in 0 I tried and got +- sqr(5/8) but i don't how to make it to radian.
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Determine all solutions of the equation in radians
find cosx/2, given that sec x = 4 and x terminates in 0 ***
cosx=1/secx=1/4 (In quadrant I where cos>0)

cos(x/2)=√(5/8)
use inverse cos key on calculator set to radians,then punch in √(5/8)
cos(x/2)≈0.659 radians