5. The third angle of a triangle

$$\begin{array}{lcl}If\;one\;angle\;in\;a\;triangle\;is\;\frac{\pi }{6}\;and\;another\\\ is\;\frac{\pi }{3}.\;The\;third\;angle\;must\;then\;be\\ \\ (F)\;\frac{\pi }{6}\\ \\ (G)\;\frac{\pi }{5}\\ \\ (H)\;\frac{\pi }{4}\\ \\ (J)\;\frac{\pi }{3}\\ \\ (K)\;\frac{\pi }{2}\\ \end{array}$$