C-10-Q041mediumsingle_mcqcos60∘=?\cos 60^\circ = ?cos60∘=?a32\dfrac{\sqrt{3}}{2}23b12\dfrac{1}{2}21c111d12\dfrac{1}{\sqrt{2}}21ব্যাখ্যাcos60∘=12\cos 60^\circ = \dfrac{1}{2}cos60∘=21 is a standard value. Note that cos60∘=sin30∘\cos 60^\circ = \sin 30^\circcos60∘=sin30∘ because 60∘60^\circ60∘ and 30∘30^\circ30∘ are complementary angles.