Răspuns:
Explicație pas cu pas:
duci AE ⊥ BC - E∈BC
ΔABC- AB=AC=25 cm
- BC=30 cm
BE= 30/2=15 cm ( AE- mediana )
Δ AEB- ∡E= 90°
- AB=25 cm
- BE= 15
AE²= 25²-15²
AE²=625-225
AE²=400
AE=√400
AE=20 cm
-
AE*BC=BD*AC
20*30=BD*25
600=BD*25
BD= 600:25
BD= 24 cm
-
ΔBDC -∡E=90°
CD²=BC²-BD²
CD²=30²-24²
CD²=900-576
CD²=324
CD=√324
CD= 18 cm
-
AD= 25-18
AD= 7 cm
-
ΔABD- AD=7 cm
-AB= 25 cm
- BD= 20 cm
-
P ΔABD= 7+25+24= 56 cm
