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sin20x=? plz ans.this

sunny kumar , 15 Years ago

Grade 12

1 Answers

Jitender Singh

Last Activity: 10 Years ago

Ans:Hello student, please find answer to your question
$sin(20x) = 2sin(10x)cos(10x)$
$sin(20x) = 2(2sin(5x)cos(5x))cos(10x)$
$sin(20x) = 4sin(5x)cos(5x)(cos^{2}(5x)-sin^{2}(5x))$
$sin(20x) = 4sin(5x)cos(5x)(cos(5x)+sin(5x))(cos(5x)-sin(5x))$ Now, break 5x into 3x & 2x which can be easily convertible into sinx form
$sin(2x) = 2sin(x)cos(x)$
$sin(3x) = 3sin(x)-4sin^{3}(x)$

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