A(ABCD) = A(∆BAD) + A(∆BDC)
In ∆BAD, m∠BAD = 90°, l(AB) = 40m, l(AD) = 9m
A(∆BAD) = (1/2) x product of sides forming the right angle
= (1/2) x l(AB) x l(AD)
= (1/2) x 40 x 9 = 180 sq. m
In ∆BDC, l(BT) = 13m, l(CD) = 60m
A(∆BDC) = (1/2) x base x height
= (1/2) x l(CD) x l(BT)
= (1/2) x 60 x 13
= 390 sq. m A (ABCD)
= A(∆BAD) + A(∆BDC)
= 180 + 390
= 570 sq. m
∴ The area of ABCD is 570 sq.m.
