Question

What is a possible value of sin(theta) when cos2(theta)=0.21

A) 0.32
B) 0.37
C) 0.63
D) 0.63

Answer 1

we know that

cos²(theta)=0.21
sin²(theta)+cos²(theta)=1
sin²(theta)=1-cos²(theta)------> sin²(theta)=1-(0.21)-----> 0.79
sin(theta)=√0.79
sin(theta)=0.89

the answer is
the value of sin(theta) is 0.89