In the given triangle, two angles are 30° and 60°, => Third angle = 90° 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 : $$sqrt{3}$$ : 2 Length of the side opposite the 30° angle = $$9sqrt{3}$$ cm => Length of side opposite the 60° angle = $$sqrt{3} imes 9sqrt{3} = 27$$ cm => Ans - (A)