AB is a chord of the circle and its center is “O”. ON is perpendicular to AB. If the length of AB=20 cm, ON-(2√11) cm, find the radius (in cm) of the circle.
D and E are points on side AB and AC of ΔABC. DE is parallel to BC. If AD:DB = 2:3 and area of ΔABC is 100 sq cm, what is the area (in sq cm) of quadrilateral BDEC?