Let a represent an interior angle; e represent an exterior angle. A section of the polygon is down in the diagram. \(\frac{e}{a}\) = \(\frac{l}{11}\) given a = 11e a + e = 180o(angles on a straight line) 11e + e = 180o 12e = 180o e = \(\frac{180^o}{12}\) = 15o Hence, number of sides = \(\frac{360^o}{\tect{size of one exterior angle}\) = \(\frac{360^o}{14^o}\) = 24