Răspuns:
Explicație pas cu pas:
13)∠AOC+∠COB=90° ∠AOB=90 , C fiind in interiorul ∠AOB
14) a)∠A=1/4(90-∠A) x=1/4(90-x) 4x=90-x 5x=90 ∠A=18°
b) ∠A=1/5(180-∠A) X=1/5(180-X) 5x=180-x 6x=180 ∠A=30°
c) ∠A=2(90-∠A) x=2(190-x) x=180-2x 3x=180 x=60°
