Let θ represent an angle in the second quadrant such that sin (θ) = 4/5
a.) What is cos (θ)? (for my answer I got cos (θ) = -3 / 5, but not sure if I'm right)
b.) Find sin (θ / 2) and cos (θ / 2) [hard time with this question]
If you could give step by step help so I can practice this later, I would really appreciate it!