SSC CHSL 9 Jan 2017 Shift 1 Paper

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 $\sqrt{3}$ times as long as the side opposite the 30° angle.
The ratio of sides opposite 30°, 60° and 90° angles =1 : $\sqrt{3}$ : 2
Length of the side opposite the 60° angle = $6\sqrt{3}$ cm
⇒ Length of side opposite the 90° angle = $\frac{2}{\sqrt{3}}\times 6\sqrt{3}=12$ cm