3) a) <B=180°-<C=180°-135°=45°
b) Fie CE _|_ AB => tr. CEB dr. isoscel => CE=BE=BC/√2=6√2/√2=6 cm
CD=AB-BE=15-6=9 cm
Aria = (AB+CD)×CE/2=(15+9)×6/2=24×3=72 cm2
4) a) M mij BC => AM mediana => AM=MC=MB=6 cm
BC=MC+MB=6×2=12 cm
b) Din Teorema <75° => AD=BC/4=12/4=3 cm
