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  1. #1
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    help

    Given tan x = b/a , find the value of a cos 2x + b sin 2x in terms of a
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  2. #2
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    Quote Originally Posted by mathaddict View Post
    Given tan x = b/a , find the value of a cos 2x + b sin 2x in terms of a
    \tan x = \frac{b}{a} \Rightarrow \sin x = \frac{b}{\sqrt{a^2 + b^2}} and \cos x = \frac{a}{\sqrt{a^2 + b^2}}.

    Substitute these results into \cos (2x) = \cos^2 x - \sin^2 x and \sin (2x) = 2 \sin x \cos x.

    Simplify the resulting expression.
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