C-09-Q175mediumsingle_mcqcos60∘⋅cos30∘+sin60∘⋅sin30∘=?\cos 60^\circ \cdot \cos 30^\circ + \sin 60^\circ \cdot \sin 30^\circ = ?cos60∘⋅cos30∘+sin60∘⋅sin30∘=?acos30∘\cos 30^\circcos30∘bsin30∘\sin 30^\circsin30∘ccos60∘\cos 60^\circcos60∘dcos90∘\cos 90^\circcos90∘ব্যাখ্যাThis is the expansion of cos(60∘−30∘)=cos30∘\cos(60^\circ-30^\circ)=\cos 30^\circcos(60∘−30∘)=cos30∘. Both forms evaluate to 32\tfrac{\sqrt3}{2}23.