Question

is it right to say cos(60°+30°)=cos60° cos30°-sin60° sin30°

Answer 1

HOPE IT WILL HELP YOU

Answer 2

An expression obtained by a finite number of the fundamental operations of algebra upon symbols representing numbers.

According to the question,

$cos(60^{\circ }+30^{\circ} )=cos60^{\circ} cos30^{\circ}) -sin60^{\circ }sin30^{\circ}$

$cos90^{\circ }=\frac{1}{2}\times \frac{\sqrt{3} }{2} -\frac{\sqrt{3} }{2}\times\frac{1}{2}$

$0=\frac{\sqrt{3} }{4} -\frac{\sqrt{3} }{4}$

$0=0$
LHS=RHS

Hence proved