Answers

2015-09-11T10:38:32+05:30
Sinπ/10×sin13π/10 =-sinπ/10×sin3π/10 =-sinπ/10×Cos2π/10 =-sinπ/10×[1-2(Sinπ/10)^2] =-(V5-1)/4 [1-2[(V5-1)/4]^2] =-(V5-1)/4 * 4(V5+1)/16 =-1/4 Sin 18=sin π/10 = (V5-1)/4
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