Explicație pas cu pas:
a) PB = BC = CP => ΔPBC echilateral
∢PBC = ∢PCB = 60°
∢ABP = ∢ABC - ∢PBC
∢ACP = ∢ACB - ∢PCB
=> ∢ABP = ∢ACP
ΔABC isoscel => AB = AC
=> ΔABP = ΔACP (cazul L.U.L.)
b) ∢B = ∢C = 2(∢A)
2(∢A) + 2(∢A) + ∢A = 180°
∢A = 180° ÷ 5 = 36°
∢B = ∢C = 72°
∢ACP = ∢ACB - ∢PCB = 72° - 60 ° = 12°
∢CAP = ∢A ÷ 2 = 36° ÷ 2 = 18°
∢APC = 180° - (∢ACP + ∢CAP) = 180° - (12° + 18°) = 150°
∢ACP = 12°
∢CAP = 18°
∢APC = 150°