2 cos-1 x = cos-1 (2x2 -1)
put x= cos theta
and use 2cos^2theta-1 =cos2theta
and u will get the answer
hope this helps
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2 cos-1 x = cos-1 (2x2 -1)
put x= cos theta
and use 2cos^2theta-1 =cos2theta
and u will get the answer
hope this helps