General
Friday, May 9, 2014
Question
If
$$sin(x)=2cos(x)$$
Find :
$$cos2x$$
.
.
1#
If
$$sin(x)=2cos(x)$$
So :
$$tan(x)=2$$
So
$$tan(2x)=\frac{2tan(x)}{1-tan^2(x)}=\frac{-4}{3}$$
So as shown in the figure below :
$$cos(2x)=\frac{3}{5}$$
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