[tex]\cos \theta = \dfrac{\text{Base}}{\text{Hypotenuse}}\\ \\\\~~~~~~~=\dfrac{3}{\sqrt{3^2 +2^2}}~~~~~~~;[\text{Pythagorean theorem.}]\\\\\\~~~~~~~=\dfrac{3}{\sqrt{9+4}}\\\\\\~~~~~~~=\dfrac{3}{\sqrt{13}}[/tex]
