Trigonometry
Find the quadrant in which x+yx+yx+y lies. Use trigonometric identities.
cosx=511\cos x=\frac{5}{11}cosx=115, siny=−18\sin y=-\frac18siny=−81, xxx in fourth quadrant, yyy in third quadrant
Quadrant I
Quadrant II
Quadrant III
Quadrant IV