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Atkinsoha
PreCalc & Trig, picture below, please show your work..
Firstly, calculate the hypotenuse, then find cos(theta), then find theta. Once you have found theta, use it to calculate cos(theta/2). However, if you are required to use identities (which I doubt), remember that \(cos^2(\theta) = \frac{1+cos(\theta)}{2}\).