Incorrect. You can set up a right triangle and give the side opposite angle A length 2 and the hypotenuse length 3. Then $\displaystyle{{2}}^{{2}}+{{a}}^{{2}}={{3}}^{{2}}\usepackage{cmbright}\Huge\$ . Solve this equation to find the length of the adjacent side to angle A, then use the definitions of the trigonometric functions.