Question

Va rog ajutați-ma mult de tot!​

Answer 1

5)

P = 80 = 4l => l = 80 : 4 = 20 cm

∡B= 60°

AB = BC  } => ΔABC echilateral => AC = 20 cm

BO ⊥ AC  = AC√3/2 = 20√3/2 = 10√3 cm

BO = BD/2 => BD = 2·BO = 2·10√3 = 20√3 cm

6)

ABCD - isoscel => ∡A = 180° - ∡B = 180° - 120° = 60°

AC - bisectoare => ∡BAC = 60°/2 = 30°  (1)

∡ACB = 180° - (120 + 30) = 180 - 150 = 30°  (2)

Din (1) si (2) => ΔABC = isoscel => AB = BC  = 12 cm

ABCD - isoscel => CD = 12 cm

Ducem BE ⊥ AD

cosA = AE/AB => 1/2 = AE/12 => AE = 12/2 = 6 cm

ABCD = isoscel => AD = 2AE + BC = 12 + 12 = 24 cm

P = AB + BC + CD + DA = 36 + 24 = 60 cm