Răspuns:
a) Aria unui triunghi dreptunghic este semiprodusul catetelor.
T. bisect.
BA/AD = BC/CD
BA/12 = BC/36 => BA = BC/3
T. Pitagora
BA^2 + 48^2 = 9BA^2
8BA^2 = 48^2
BA^2 = 6×48 = 288 => BA = 12rad2 cm
Aria = (12rad2 × 48)/2 = 288rad2 cm^2
b) ED || BC =>tr. AED ~ tr. ABC =>AE/AB=AD/AC=ED/BC
AE/12rad2 = 12/48 = 1/4
=>AE = 3rad2 cm = BF
ED/36rad2 = 1/4 => ED = BF = 9rad2
Perimetrul = 2×3rad2 + 2×9rad2 = 24rad2 cm
