Bonsoir,
Aire rectangle= L * l
Aire ABCD= 8*4= 32
Aire triangle= ( L X l)/2
Aire IAL= (x(4-x))/2= (4x-x²)/2
Aire LDK= (x(8-x))/2= (8x-x²)/2
Aire KCJ= (x(4-x))/2= (4x-x²)/2
Aire IBJ= (x(8-x))/2= (8x-x²)/2
Aire IJKL= Aire ABCD- (Aire IAL+ Aire LDK+ Aire KCJ+ Aire IBJ
A= 32 - [(4x-x²)/2+(8x-x²)/2+(4x-x²)/2+(8x-x²)/2 ]
A= 32-4x+x²-8x+x²-4x+x²-8x+x²
A= 32 - (-4x²+24x)/2
A= 32- (-2x²+12x)
A= 32+2x²-12x
A= 2x²-12x+32
