a. MP² = MN² + NP² adevarat
⇒ Δ MNP drept mas<( N) = 90 °
b. perim = 7 +21 +16 = 44 cm
semiperimetrul = 44 /2 cm = 22cm
aria² = 22 · ( 22 -7) · ( 22 - 21) ·( 22 -16) formula Heron
aria² =22 · 15 ·1·6 = 11·2· 5·3·2·3 = 11· 5 ·4·9
aria = √11·√5·√4·√9 = 6·√55 cm