Incorrect. Convert the angles to degrees:

$\displaystyle\frac{{{3}\pi}}{{4}}={{135}}^{\circ},\frac{{{3}\pi}}{{2}}={{270}}^{\circ},\frac{{{5}\pi}}{{3}}={{300}}^{\circ}\usepackage{cmbright}\Huge\$

Find the coordinates of the point where each one of these angles intersects the unit circle. The value of cosine is the x-coordinate and the value of sine is the y-coordinate of this point.