Question

LHS = 2 sin 2 40 cos 80 cos 40 2 sin 2 20. and - LHS = LHS = 12 singolo cos 40, sin se (2 sin 40 cos 40) cos 80 2 sin 40 cos 40 cos 80 ) sin 40 2 sina 20 72 sin 20 cos 20 ) 2 sin? 20 LHS = X

JEE/Engineering Exams

Maths

Solution

145

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the ( frac{2 sin ^{2} 4 theta cos 4 theta}{cos 8 theta times 2 sin ^{2} 2 theta} ) So, ( frac{2 sin 4 theta times sin 4 theta times cos 4 theta}{cos 8 theta times 2 sin ^{2} 2 theta} ) ( Rightarrow frac{2 sin 4 theta cos 4 theta times sin 40}{cos 8 theta} frac{sin ^{2} 2 theta}{2 sin ^{2} theta} ) ( sin 8 theta=2 sin 40 cos 4 theta ) ( sin 4 theta=2 sin theta cos 2 theta ) So, ( quad frac{sin 8 theta}{cos 8 theta} times frac{x sin 2 theta cos 2 theta}{x sin ^{2} 2 theta} ) ( =tan 8 theta times cot 2 theta )