Troubleshooting Trig Identities and Equations

[zizkio46]

Homework Statement

cos(squared)x = sinx-1/2

Homework Equations

cos(squared)x= 1-sin(squared)x

The Attempt at a Solution

I tried everything but my answer does not match my answers in calculator

 

[jhicks]

If $$cos^2(x) = sin(x)-0.5$$ and $$cos^2(x) = 1-sin^2(x)$$, then wouldn't you agree that $$sin(x)-0.5 = 1-sin^2(x)$$? That's a quadratic equation.