EXPERTS PLS. HELP!

THE SIDES OF A QUADRILATERAL , TAKEN IN RDER R 5,12,14&15m. RESPECTIVELY & D ANGLES CONTAINED BY THE FIRST 2 SIDES IS A RIGHT ANGLE. FIND ITS AREA???

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 the first two sidesw and a diagonal form a right triangle..

THE DIAGONAL IS 13m..as it is a part of a right triangle..

so,1/2*5*12=30..

now,by heron's formula,other triangle..

s=(13+14+15)/2=16..

area=root under (s(s-a)(s-b)(s-c))=root96..

add 30 to root96..

 sorry s=21;