the given triangle, two angles are 90° and 60°, ⇒ Third angle = 30° In a 30-60-90 triangle, the hypotenuse is always twice as long as the side opposite the 30° angle and the side opposite the 60° angle is √3 times as long as the side opposite the 30° angle. The ratio of sides opposite 30°, 60° and 90° angles =1 : √3 : 2 Length of the side opposite the 60° angle = 6√3 cm ⇒ Length of side opposite the 90° angle =