Răspuns:
Explicație pas cu pas:
a)
3*arc AB= 4 *arc BC
arc AB= (4* arc BC)/ 3
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arc AD= 2* arc BC
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6* arc CD = 5 *arc AD
6*arc CD = 5*( 2 arc BC)
6*arc CD= 10* arc BC
arc CD= (10 arc BC) /6
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²⁾(4*arc BC)/3 + ⁶⁾2*arc BC+ (10*arc BC) /6 + ⁶⁾arc BC= ⁶⁾360°
8*arc BC+ 12*arc BC+ 10 *arc BC+6*arc BC= 2160°
36* arc BC= 2160°
arc BC= 2160:30
arc BC= 60°
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3*arc AB= 4*arc BC
3*arc AB= 4*60
3*arc AB= 240°
arc AB= 240:3
arc AB= 80
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arc AD= 2*arc BC
arc AD= 2*60
arc AD= 120°
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6*arc CD =5*arc AD
6*arcCD= 5*120
6*arc CD= 600
arc CD= 600:6
arc CD= 100°
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b)
∡A= 160:2=80°
∡B=(120+100):2= 110°
∡C= (80+120):2=100°
∡D= (80+60):2= 70°
