Réponses

2013-10-03T15:51:04+02:00
32)

HC = BC - AD = 48 - 27 = 21
cos (angle C) = HC / CD  = 21 /  75
angle C  = 73,7°

sin (angle C) =  HD / DC
HD = sin (angle C)* DC  sin (73,7) * 75 = 72°

aire = 27 * 72 + ( 21 * 72 ) / 2  = 1944 + 756  = 2700 m^2  = 27 ares


33)

AB^2 = AC^2 + BC^2
AC^2 = AB^2 - BC^2 = 81 + 51.84 = 29,16
AC = 5.4

AI^2= IC^2 + AC^2 = 3.6^2 + 5.4^2 = 42.12
AI = 6.5

BJ^2= CJ^2 + BC^2 = 2,7^2 + 7,2^2 = 59.13
AI = 7.7





2013-10-03T16:15:45+02:00
Bonjour
DH² = 75² -21² = 5626 - 441 = 5 184
DH = V5184 = 72m  (V = racine de )
ABDH = 27 x 72 = 1 944 m²
DHC = (72 x 75)/2 = 2 700 m²
superficie totale = 4644 m² ou 46.44 ares

AC² = AB² - BC²
AC² = 81 - 51.84 = 29.16
AC = V29.16 = 5.4 m

AI est la médiane donc BI = BC = 3.6 m
AI² = AC² + CI²
AI² = 29.16 + 12.96 = 42.12
AI = V42.12 = 6.48 = 6.4899 m ou 6490 mm

J est le milieu de AC donc AJ = AC = 2.7
BJ² = BC² + CJ²
BJ² = 51.84 + 7.29 = 59.13
BJ = V59.13
= 7.6896 = 7690 mm