Answers

2014-05-23T17:15:03+05:30
 \frac{cos (50)}{2 sin (50)}= \frac{sin(90-50)}{2 sin(40)}= \frac{sin(40)}{2 sin(40)}=0.5 ...(1)
 \frac{2}{3}tan(12)tan(78)tan(90)= \frac{2}{3}tan(12)cot(12)tan(90)= \frac{2}{3}tan(90) ....(2)
4 \frac{cosec^2(59)-tan^2(31)}{3tan^2(45)-\frac{2}{3}tan(12)tan(78)tan(90)}=\\4 \frac{sec^2(31)-tan^2(31)}{3-\frac{2}{3}tan(90)}= \\4\frac{sec^2(31)-(sec^2(31)-1)}{3-\frac{2}{3}tan(90)}= \frac{12}{3-2tan(90)}=0
...(3)
add (1) + (3)=0.5

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