Question

What is the value of   sinθ

, given that  cosθ=− 2/5  and   sinθ>0 ?

Simplify radicals and rationalize the denominator, if necessary.

 

Enter your answer in the box.

sinθ =

Answer 1

`\cos\theta=-\frac25`

`\sin\theta=\pm√(1-\cos^2\theta)=\pm\frac{√(21)}5`

Take the positive root, since it's given that
`\sin\theta>0`.


`\sin\theta=\frac{√(21)}5`