Question

find area of quadrilateral ABCD in which AB =9cm ,BC=15cm,CD=12cm and BD=15cm​

Answer 1

in triangle DCB,

area=1/2*b*h

1/2*12*15

=90cm

in triangle ADB,

area=1/2*9*15

=67.5cm sq.

area of quad.=90+67.5

=157.5cm sq.

Answer 2

Answer:

Step-by-step explanation:

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

Area of trianlge= sqrt(s(s-a)(s-b)(s-c))

FOR area of triangle ABC

s=(7+6+9)/2=11

area of triangle ABC=sqrt(11(11-7)(11-6)(11-9))

=sqrt(440)

= 20.9761

similarly,

area of triangle ADC=54

therefore area of quadrilateral ABCD=20.9761+ 54

=74.9761

ANOTHER WAY...

let it be 2 triangles rather than 1 big quadrilateral.

ABC = 7/6/9 and ADC = 15/12/9

total area

= √(11 * 4 * 5 * 2) + (12 * 9) / 2

= 2√110 + 54

= 74.976177

=~ 75 cm^2