Double & half angle

big 8. If sin A - , what is the value of cos 2A? 1) - 2) 3) 4 9. If cos = =, then what is cos 20? 1) 2) 3) 4) 16 N/W 10. For all values of @ for which the expressions are defined, prove the following is an identity: cos @sin &+ cos @ = tan O+ sec e cos a of inslaviups . tan & 1 1. Prove the following identity: cot @ + 1 = sec' a 12. Prove that the equation shown below is an identity for all values for which the functions are defined: csc 0 . sin 0 . cot 0 = cos 0