Using trigonometry and Fig. 2 in the ballistic pendulum write-up, show that the height h the pendulum rises after capturing the ball is given by: h=R(1-cosθ)
Figure two is here: http://imgur.com/W9nvVZT
The Attempt at a Solution
So in order for the height to increase I understand that R is the length of the pendulum. θ is the maximum deflection, so since R can't be negative that means cos(θ) must return a negative answer in order for the height to increase. So how do I prove that cos(θ) in this instance will be a negative number, thus making the height increase.