Question

is it right to say that cos (60 - 30) =cos 60 cos 30+sin 60 sin 30. Give reason​

Answer 1

yes that is right because

cos(a-b)=cosacosb+sinasinb

this is ur answer

please MARK as BRAINLIST answer

Answer 2

$yes \: it \: is \: correct \: because \\ cos(a - b) = \cos(a) \cos(b) + \sin(a ) \sin(b) \\ we \: can \: verify \: this \: by \: given \: example \\ \\ cos(60 - 30) = \cos(60 \ ) \cos( 30) + \sin(60) \sin(30) \\ - > \cos(30) = \frac{ \sqrt{3} }{4} + \frac{ { \sqrt{3} } }{4} \\ - > \frac{ \sqrt{3} }{2} = \frac{2 \sqrt{3} }{4} \\ \\ - > \frac{ \sqrt{3} }{2} = \frac{ \sqrt{3} }{2 } \\ \\ - > lhs = rhs \\ \\ so \: the \: given \: example \: is \: correct$