C-09-Q121mediumsingle_mcqcos30∘=?\cos 30^\circ = ?cos30∘=?a12\dfrac{1}{2}21b12\dfrac{1}{\sqrt{2}}21c32\dfrac{\sqrt{3}}{2}23d3\sqrt{3}3ব্যাখ্যাcos30∘\cos30^\circcos30∘ is the ratio of the adjacent side to the hypotenuse, OMOP=a32a=32\dfrac{OM}{OP}=\dfrac{a\sqrt3}{2a}=\dfrac{\sqrt3}{2}OPOM=2aa3=23. This is a standard value.