Question

In quadrilateral ABCD, angleB = angleD= 90°, AB = 7 cm, AC = 25 cm, CD = 20 cm. Find the area of ABCD​.​

Answer 1

Answer:

Correct option is

A

True

Area quadrilateral ABCD= area of triangle ABC+area of triangle ACD

ar△ABC=

s(s−a)(s−b)(s−c)

,s=

2

a+b+c

=

2

9+6+7

=11㎝

∴ar△ABC=

11(11−9)(11−6)(11−7)

=

11×2×5×4

=2

110

㎠

=10.48×2=20.96㎠

ar△ACD=

s(s−a)(s−b)(s−c)

,s=

2

a+b+c

=

2

15+9+12

=18㎝

∴ar△ACD=

18(18−15)(18−9)(18−12)

=

18×3×9×6

=

6×3×3×9×6

=3×3×6=54㎠

∴ar△ABCD=20.96+54=74.96㎠