C-09-Q127mediumsingle_mcqcos60∘=?\cos 60^\circ = ?cos60∘=?a12\dfrac{1}{2}21b12\dfrac{1}{\sqrt{2}}21c32\dfrac{\sqrt{3}}{2}23d111ব্যাখ্যাCosine of 60∘60^\circ60∘ equals the sine of its complement 30∘30^\circ30∘, and sin30∘=12\sin 30^\circ = \dfrac{1}{2}sin30∘=21, so cos60∘=12\cos 60^\circ = \dfrac{1}{2}cos60∘=21.