Question

find the area of quadrilateral ABCD in which AB=7cm BC=6cm CD=12cm DA=15cm and AC=9cm

Answer 1

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



======== s=(7+6+9)/2=11 


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




=[tex] \sqrt{440 } [/tex]




= 20.9761 





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area of triangle ADC=54 

------------------------- area of quadrilateral ABCD=20.9761+ 54 


                                 =74.9761

Answer 2

area of the quadrilateral = area of ABC + ADC
area of ADC = √{(s-a)(s-b)(s-c)}
√(18-15)(18-12)(18-9)
√(3)(6)(9)
3√2

area of ABC
√(s-a)(s-b)(s-c)
√(11-9)(11-7)(11-6)
2√10

therefore area of ABCD =3√2+2√10 unit²