## a1234 one year ago Evaluate the two trigonometric functions using its period as an aid. 1. cos (9pi/2) = ______ Answer - 0 2. cos (-9pi/2) = ______ Answer - 0

1. anonymous

$\cos \frac{ 9 \pi }{ 2 }=\cos \left( 4 \pi+\frac{ \pi }{ 2 } \right)=\cos \frac{ \pi }{ 2 }=0$ $\cos \left( -\theta \right)=\cos\theta\$

2. a1234

So are both my answers correct?

3. anonymous

yes