Question

Question #3cb9b

Answer 1

`cos(x)=+-sqrt(1-sin^2(x))`

Explanation:

Use the pythagorean trigonometric identity:

`sin^2(x)+cos^2(x)=1`

Solve for cosine

`cos(x)=+-sqrt(1-sin^2(x))`

And then substitute your value for sine

Be aware of the sign

For each angle, there is only one value for cosine (or sine)

In quadrant 1 and 4 cosine is positive

In quadrant 2 and 3 cosine is negative