Half Angle Formulas: No Negative Square Roots

[armolinasf]

Homework Statement

I'm just wondering why we don't have to worry about the possibility of taking the square root of a negative number when dealing with the half angle formulas for sine and cosine. Thanks.

 

[olivermsun]

What are the maximum and minimum possible values for sin x and cos x?

 

[armolinasf]

wow! I got it, thanks.