Let $f ( x , y ) = \sin ( x + y ) + \sin x + \sin y$ . Then f has a relative minimum at

A) $\left( - \frac { 5 \pi } { 3 } , \frac { 5 \pi } { 3 } \right)$
B) $\left( \frac { 5 \pi } { 3 } , \frac { 5 \pi } { 3 } \right)$
C) $\left( \frac { \pi } { 3 } , \frac { \pi } { 3 } \right)$
D) $\left( - \frac { \pi } { 3 } , \frac { \pi } { 3 } \right)$
E) $\left( \frac { 5 \pi } { 3 } , - \frac { 5 \pi } { 3 } \right)$

Question

Let $f ( x , y ) = \sin ( x + y ) + \sin x + \sin y$ . Then f has a relative minimum at

A) $\left( - \frac { 5 \pi } { 3 } , \frac { 5 \pi } { 3 } \right)$
B) $\left( \frac { 5 \pi } { 3 } , \frac { 5 \pi } { 3 } \right)$
C) $\left( \frac { \pi } { 3 } , \frac { \pi } { 3 } \right)$
D) $\left( - \frac { \pi } { 3 } , \frac { \pi } { 3 } \right)$
E) $\left( \frac { 5 \pi } { 3 } , - \frac { 5 \pi } { 3 } \right)$

Quizplus · Accepted Answer

The Answer of Let $f ( x , y ) = \sin ( x + y ) + \sin x + \sin y$ . Then f has a relative minimum at

A) $\left( - \frac { 5 \pi } { 3 } , \frac { 5 \pi } { 3 } \right)$
B) $\left( \frac { 5 \pi } { 3 } , \frac { 5 \pi } { 3 } \right)$
C) $\left( \frac { \pi } { 3 } , \frac { \pi } { 3 } \right)$
D) $\left( - \frac { \pi } { 3 } , \frac { \pi } { 3 } \right)$
E) $\left( \frac { 5 \pi } { 3 } , - \frac { 5 \pi } { 3 } \right)$

Let f(x,y)=sin⁡(x+y)+sin⁡x+sin⁡yf ( x , y ) = \sin ( x + y ) + \sin x + \sin yf(x,y)=sin(x+y)+sinx+siny

Let $f ( x , y ) = \sin ( x + y ) + \sin x + \sin y$