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Y-tan-1-cos-2x-sin-2x-sin2x-cos-2x-then-find-dy-dx - Mathematics and Statistics

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Question

If Y = tan-1 `[(cos 2x - sin 2x)/(sin2x + cos 2x)]` then find `(dy)/(dx)`

Sum

Solution

Let y = tan-1 `[(cos 2x - sin 2x)/(sin2x + cos 2x)]`

y = tan-1 `[((cos 2x) /(cos 2x)- (sin2x)/(cos 2x))/((sin2x) /(cos 2x)- (cos 2x)/(cos 2x))]`

y = tan-1 `((1 - tan 2x)/(1 + tan 2x))`

y = tan-1  `[(tan π/4 - tan 2x)/(1 + tan π/4. tan 2x)]`

y = tan-1 `[tan ( π/4 - 2x)]`

y = π/4 - 2x

Diff w.r.t.x

`therefore (dy)/(dx) = -2`

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2013-2014 (October)

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