Question

дано:
sint = 4/5
Найти:
sin2t - ?
cos2t - ?

Answer 1

Ответ:

sin²t+cos²t=1

cos²t=1-(4/5)=1-16/25=25/25- 16/25=9/25

cost=√(9/25)=3/5

sin2t=2sintcost=2* 3/5 *4/5=24/25

cos2t=cos²t-sin²t=(3/5)²-(4/5)²=9/25-16/25= -7/25