1.

\frac { \operatorname { cos } 70 ^ { \circ } } { \operatorname { sin } 20 ^ { \circ } } + \frac { \operatorname { cos } 59 ^ { \circ } } { \operatorname { sin } 31 ^ { \circ } } - 8 \operatorname { sin } ^ { 2 } 30 ^ { \circ } = 0

Answer»

sin(90-20)=cos70same wisecos59= sin31so 1+1-(8*1/4)=2-2=0



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