im supposed to eliminate A from the pair of equations
ive learnt most trig identities i think, up to the double angle identities etc.
ive done several problems like this but here im really stuck
i passed through those already, including the sin2A double angle identity which i already figured might be totally irrelevant to this problem. but where do i go from cos4A? i really didnt need someone to repeat these identities to me. im actually stuck.