Explicație pas cu pas:
cosB=0,6=6/10=3/5=BE/BC. Fie BE=3x, BC=5x=CD=AD
⇒AB=AF+FE+EB=3x+5x+3x=11x=88, ⇒ x=8. Atunci, BC=5·8=40=CD=AD.
CD=40cm.
Din ΔBCE, CE²=BC²-BE²=40²-24²=8²·5²-8²·3²=8²·(5²-3²)=8²·4²=32². Deci CE=32.
Din ΔACE, AE=AB-EB=88-3·8=88-24=64cm, AC²=AE²+CE²=64²+32²=32²·2²-32²·1=32²·(2²-1)=32²·3. Deci AE=32√3cm=BD.
Aria(ABCD)=(AB+CD)·CE/2=(88+40)·32/2=128·16=2048cm².
SPER CA ESTE BINE!
