bsr j aurait besoin aide pour l exercice 28 de maths les question A et B

bonjour
MH² = 7.8² - 3² = 51.84
MH = √ 51.84 = 7.2 cm
HT² = 7.5² - 7.2² = 4.41
HT = √4.41 = 2.1 cm
P = 5.1 + 7.5 + 7.8 = 20.4 cm