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Cos2a=1-2sin^2a for all values of a.
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Cos2a=1-2sin^2a for all values of a.

User Waqas Sultan
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2 Answers

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true (just did this on apex)

User Rowbear
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cos2a= cos^(2) a- sin^(2) a \\ but \ cos^(2) a + sin^(2) a=1 \\ i.e. \ cos^(2) a=1- sin^(2) a
Therefore,

cos2a=1- sin^(2) a- sin^(2) a \\ =1-2 sin^(2) a
User Kiran Bhat
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