- #1

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## Main Question or Discussion Point

Given that sin

Without using Calculator,

Since cos(-

With Calculator,

Subst -26.57 into cos(-

One is positive, another is negative. Which is which?

*A*= [tex]\frac{-1}{\sqrt{5}}[/tex] where*A*is more than 180 degrees and less than 270 degrees. Find the value of cos(-*A*).Without using Calculator,

Since cos(-

*A*) = cos*A*, and that*A*is in the 3rd quadrant, then after solving for the hypotenuse, adjacent and opposite, I got:**[tex]\frac{-2}{\sqrt{5}}[/tex]**With Calculator,

*A*= Inverse Sin([tex]\frac{-1}{\sqrt{5}}[/tex]) = -26.57 (4 T.C.)Subst -26.57 into cos(-

*A*), I got:**[tex]\frac{2}{\sqrt{5}}[/tex]**One is positive, another is negative. Which is which?