Find the area of a quadrilateral ABCD in which AB = 42 cm, BC = 21 cm, CD = 29 cm, DA = 34 cm and diagonal BD = 20 cm.

In ∆ABD;


AB = a = 42 cm, BD = b = 20 cm, DA = c = 34 cm


Let a, b and c are the sides of triangle and s is


the semi-perimeter, then its area is given by:



A = where


= = 48


A1 =


A1 = = m2


In ∆BCD;


BC = a = 21 cm, DC = b = 29 cm, BD = c = 20 cm


Let a, b and c are the sides of triangle and s is


the semi-perimeter, then its area is given by:


A = where


= = 35


A2 =


A2 = = m2


Therefore area of quadrilateral ABCD = A1 + A2 = 336+210 = 546 cm2


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