Question

The number of multiples of
${10}^{44}$
that divides
${10}^{55}$
is​

Answer 1

LHS :

cos2xcos2x−cos3xcos29x

=21[2cos2xcos2x−2cos3xcos29x]

=21[cos[(2x+2x)+cos(2x−2x)]−[cos(3x+29x)+cos(29x−3x)]]

=21[cos25x+cos23x−cos215x−cos23x]

=21[cos25x−cos215x