Use the ratio of a 30-60-90 with the side opposite the 90 degree angle is 2x, the side opposite the 30 degree angle is x and the side opposite the 60 degree angle is x sqrt 3.If BC is 2 and angle CBD is 60 degrees, then angle DCB is 30 degrees. Therefore the side opposite the hypotenuse of BC is 1 (half of BC) and the side opposite the 60 degree angle is 1sqrt 3 or just sqrt 3.