I'm not sure how to start the question. It will need a double angle formula later.
Hello, Stuck Man!
Yes, both double-angle identities are useful.
As skeeter pointed out: .12. The diagram shows a kite who leading diagonal is a diameter of the circle.
Find the exact values of: .Code:Z * * * _ * * | *√5* * * | * * X o | o Y \ | / * \ | / * * \ | / * * 3 \ | / 3 * \ θ | θ / * \ | / * * \ | / * * \|/ * * * * O