## Trigonometry (10th Edition)

$\sin$(-390) = -$\frac{1}{2}$ $\cos$(-390) = $\frac{\sqrt3}{2}$ $\tan$(-390) = -$\frac{\sqrt3}{3}$ $\cot$(-390) = -$\sqrt3$ $\csc$(-390) = -2 $\sec$(-390) = $\frac{2\sqrt3}{3}$
-390$^{\circ}$ We must first fine the coterminal angle: -390$^{\circ}$ + 360$^{\circ}$ = -30$^{\circ}$ -30 is in Quadrant IV. Therefore all the trigonometric functions are negative with the exception of $\cos$ and $\sec$ $\sin$(-30) = -$\frac{1}{2}$ $\cos$(-30) = $\frac{\sqrt3}{2}$ $\tan$(-30) = -$\frac{\sqrt3}{3}$ $\cot$(-30) = -$\sqrt3$ $\csc$(-30) = -2 $\sec$(-30) = $\frac{2\sqrt3}{3}$