Calculate the area of quad. ABCD, given in Fig. (i).
Given
AD = 9 cm
BC = 8 cm
DC = 17 cm
Here Area of Quad ABCD = Area of 
ABD + Area of 
BCD
= 
x AB x AD + 
x BC x BD
By Pythagoras theorem in 
BCD
DC2 = BD2 + BC2
172 = BD2 + 82
BD2 = 172 - 82 = 289 – 64 = 225
BD = 15 cm
Similarly in 
ABD using Pythagoras theorem
BD2 = AD2 + AB2
152 = 92 + AB2
AB2 = 15 2 - 92 = 225 – 81 = 144
AB = 12 cm
Now, Area of Quad ABCD = Area of 
ABD + Area of 
BCD
= 
x AB x AD + 
x BC x BD
= 
x 12 x 9 + 
x 8 x 15 = 54 + 60 = 114 cm2
Area of Quadrilateral ABCD = 114 cm2
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