Question #3cb9b

1 Answer
Feb 1, 2018

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