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Question
Prove that `( sintheta - 2 sin ^3 theta ) = ( 2 cos ^3 theta - cos theta) tan theta`
Solution
RHS = `(2 cos^3 theta - cos theta) tan theta`
=`(2 cos^2 theta - 1) cos theta xx sin theta/ cos theta`
=`[2(1- sin^2 theta ) -1] sin theta`
=` (2-2 sin^2 theta -1 ) sin theta`
=` (1-2 sin^2 theta ) sin theta`
=`( sin theta -2 sin^3 theta )`
=LHS
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