Խնդիր 169
∪AB = 120°
r = 20 սմ
OH ⊥ AB
OH = ?
_____
∠AOB = ∪AB = 120°
AO = BO = r = 20 սմ
∠OAB = ∠OBA = (180° – 120°)/2 = 60/2 = 30°
OH = OA/2 = r/2 = 20/2 = 10 սմ
Խնդիր 170
∠BAC = 70°
∪AB = 120°
∪AC = ?
_____
∪BC = ∠BAC/2 = 70/2 = 35°
∪AC = 360° – 120° – 35° = 205°
Խնդիր 171
AB = d
∪AC : ∪CB = 7 : 2
∠BAC = ?
_____
∪AB = 180°
180/9 = 20
∪CB = 20 · 2 = 40°
∠BAC = ∪CB/2 = 40/2 = 20°
Խնդիր 173
AB = d
BC = r
∠ABC, ∠BAC, ∠ACB = ?
______
AB = 2BC
∠ACB = 90°
∠BAC = 30°
∠ABC = 60°
Խնդիր 174
∠BAD, ∠ADB = ?
______
∪BD = 110°20′
∠DOB = ∪BD = 110°20′
1° = 60′
∠AOB = 180° – 110°20′ = 69°40′
∠BAD = 180° – 90° – 69°40′ = 20°20′
∪BC = ∠BAD = 20°20′
∠ADB = ∪BC/2 = 20°20′/2 = 10°10′
Խնդիր 175
AB ⊥ CD
∠BAD = ∠ADC
∪BD = ∠BAD/2
∪AC = ∠ADC/2
∪BD = ∪AC