SOLUTION: Please help me, I am so lost. The problem is: solve the equation on the interval 0 is less than or equal to theta, theta is less that or equal to 2pi. the equation: cos theta/2 =

Algebra ->  Trigonometry-basics -> SOLUTION: Please help me, I am so lost. The problem is: solve the equation on the interval 0 is less than or equal to theta, theta is less that or equal to 2pi. the equation: cos theta/2 =      Log On


   



Question 602278: Please help me, I am so lost. The problem is: solve the equation on the interval 0 is less than or equal to theta, theta is less that or equal to 2pi.
the equation: cos theta/2 = sec theta/2

Answer by htmentor(1343) About Me  (Show Source):
You can put this solution on YOUR website!
To simplify the notation, let x=theta
cos(x/2) = sec(x/2) = 1/cos(x/2)
This gives cos^2(x/2) = 1
Using the identity cos^2(x/2) = 1/2(1+cos(x)), we can write
1/2(1+cos(x)) = 1
This gives
cos(x) = 1
On the interval 0 <= x <= 2pi, the solutions are 0 and 2pi