Area of triangle ABD = 
Area of triangle ABD = 
Area of triangle ABD = 
Area of triangle ABD = (15) (15) = 225 sq. units
Area of triangle BDC = 
Area of triangle BDC = 
Area of triangle BDC = 
Area of triangle BDC = (15) (15) = 375 sq. units
Area of Quadrilateral ABCD = Area of triangle ABD + Area of triangle BDC
Area of Quadrilateral ABCD = 225 + 375 = 600 sq. units
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BD = d1 and AC = d2
Area of triangle ABD = 
Area of triangle ABD = 
Area of triangle BDC = 
Area of triangle BDC = 
Area of Quadrilateral ABCD = Area of triangle ABD + Area of triangle BDC
Area of Quadrilateral ABCD =
+ 
Area of Quadrilateral ABCD = 
But AO + OC = AC = d2
Area of Quadrilateral ABCD = 