\( \frac{\cos ^{4} x-\sin ^{4} x}{\cos ^{2} x-\sin ^{2} x}=1 \quad \) <i in

15) Find the value of \( \sin \left(\frac{5 \pi}{3}\right) \) a) \( -\frac{\sqrt{3}}{2} \) b) \( \frac{1}{2} \) c) \( \frac{\sqrt{3}}{2} \) d) \( 0-\frac{1}{2} \)

Find all the angles \( \theta \) in \( \left[0^{\circ}, 360^{\circ}\right) \) that have a \( \sin (\theta)=\frac{-1}{2} \)

19) Find \( \sin A \) and \( \cot B \) for a right triangle given that \( b=2, c=\sqrt{29} \). a) \( O \sin A=\frac{\sqrt{29}}{5}, \cot B=\frac{2}{5} \) b) \( \sin A=\frac{5 \sqrt{29}}{29}, \cot B=\frac{5}{2} \) c) \( O \sin A=\frac{2}{5}, \cot B=\frac{5}{2} \) d) \( O \sin A=\frac{5}{29}, \cot B=\frac{5}{2} \)

Find the period of the function \( y=2 \sin \left(2 x+\frac{\pi}{2}\right) \) Period

Evaluate circular function cot for angle \( (\pi / 4) \) \[ \cot (\pi / 4)=\square \]