Question

cos3Ф+sin3Ф÷cosФ+sinФ  +cos3Ф-sin3Ф÷cosФ-sinФ

Answer 1

Cos ^3 @ + sin^3@ = ( cos @ + sin@) ( cos^2@ + sin^2@ -cos@sin@ ) and ...... ( cos^3@ -sin^3@) = ( cos@ - sin@) ( cos^2@ + sin^2@ + cos@sin@) now putting this value cos@ + sin@ canceled with cos@+ sin@ and cos@- sin@ canceled with cos@-sin@ than we get cos^2@+sin^2@ - cos@sin@ + cos^2@ + sin^2@ + cos@sin@ => 1 + 1 = 2 answer