Question

cos a=5/15 найти sin a , tg a Помогите

Answer 1

Cos a=5/15=1/3
1) cos²a+sin²a=1
   sin²a=1-cos²a
   sina=√(1-cos²a)
    sina=√(1-(1/3)²)=√(1-1/9)=√(8/9)=2/3√2
2) tga=sina/cosa=1/3:2/3√2=1/(2√2)=√2/4