Răspuns:
Explicație pas cu pas:
ex 1.
√729=√27²=27
√484=√22²=22
√1089=√33²=33
√81·16=9·4=36
√49·121=7·11=77
√114·9=√2·3·19·3²=3√114≈3·10,67≅32,031
ex2.
P=2(AB+BC)=120 cm ⇒ AB+BC=60 CM
a) AB=28 cm ⇒BC=60-28=32 cm
b)AB=2×BC ⇒2BC+BC=60 ⇒ 3BC=60 ⇒BC=20 cm
AB=60-BC=60-20=40 cm
ex 3.
∡A+∡B=180° ∡A=∡C si ∡B=∡D
a)∡A=∡B+20° ⇒∡B+20°+∡B=180° ⇒2∡B=160° ⇒∡B=80°
∡A=100°=∡C
b)∡D=∡C-10° ∡C+∡D=180° ⇒∡C+∡C-10°=180°
2∡C=190° ⇒ ∡C=∡A=95°
∡D=∡B=85°