\left. \begin{array} { r } { \operatorname { sin } ( - \frac { 3 \pi } { 4 } ) + \operatorname { cos } ( - \frac { \pi } { 4 } ) + \operatorname { sin } \frac { \pi } { 4 } \times \operatorname { cos } \frac { \pi } { 2 } } \\ { + \operatorname { cos } \frac { \pi } { 2 } \times \operatorname { sin } \frac { \pi } { 2 } } \end{array} \right.

\left. \begin{array} { r } { \operatorname { sin } ( - \frac { 3 \pi }

1.	\left. \begin{array} { r } { \operatorname { sin } ( - \frac { 3 \pi } { 4 } ) + \operatorname { cos } ( - \frac { \pi } { 4 } ) + \operatorname { sin } \frac { \pi } { 4 } \times \operatorname { cos } \frac { \pi } { 2 } } \\ { + \operatorname { cos } \frac { \pi } { 2 } \times \operatorname { sin } \frac { \pi } { 2 } } \end{array} \right.
Answer» sin(-3π/4) + cos(-π/4) + sin(π/4)cos(π/2) + cos(π/2)sin(π/2)= -1/√2 + 1/√2 + 1/√2×0 +0×1= -1/√2 +1/√2 = 0