Answer
(a) $θ=60°=\frac{\pi}{3}rad$
(b) $θ=45°=\frac{\pi}{4}rad$
Work Step by Step
Consult the table on page 436:
(a) $csc~θ=\frac{2\sqrt 3}{3}$
$\frac{1}{sin~θ}=\frac{2\sqrt 3}{3}$
$sin~θ=\frac{3}{2\sqrt 3}=\frac{3}{2\sqrt 3}\frac{\sqrt 3}{\sqrt 3}=\frac{3\sqrt 3}{2(3)}=\frac{\sqrt 3}{2}$
$θ=60°=\frac{\pi}{3}rad$
(b) $θ=45°=\frac{\pi}{4}rad$
