Question

dado cos a = 3/5 calcule sen (2a) + cos (2a)

Answer 1

sena=√1-cos²a= √1-(9/25)=√16/25=4/5

sen2a =2.sena.cosa=2.4/5.3/5= 24/25✓

cos2a =cos²a-sen²a=9/25-16/25=-7/25✓