Răspuns :
Notez: O₁= x
O₂= y
O₃= z
O₄= w
x=2y- 61
y=3z+ 2
w=2z- 5
______________________
z= ? , y= ? , z= ? , w= ?
x=2y- 61 y=3z+ 2 w=2z- 5
x=2(3z+ 2)- 61
x+ y+ z+ w= 360
[2(3z+ 2)- 61]+ (3z+ 2)+z+(2z- 5)= 360
6z+ 4- 61+3z+ 2+z+ 2z- 5=360
12z-60=360
12z =360+ 60
12z =420
z =420:12
z = 35°
y=3z+ 2 x=2(3z+ 2)- 61 w=2z- 5
y=3·35+ 2 x=2(3·35+ 2)- 61 w=2·35- 5
y=105+ 2 x=2(105+ 2)- 61 w=70- 5
y= 107° x=2·107- 61 w= 65°
x=214- 61
x=153°
probă: x+ y+ z+ w=360
153+107+ 35+ 65=360
260+100=360
360=360
b.Notez: O₁= x
O₂= y
O₃= z
x=(y+ z): 2
z= y- 52
______________________
z= ? , y= ? , z= ?
x=(y+ z): 2 z= y- 52
2x=y+ z z+52= y
x+ y+ z= 360
x+ 2x = 360
3x =360
x =360: 3
x = 120°
2x=y+ z 240°=y+ z z+52= y
2·120= y+z 240=z+ 52+ z 94+52=y
240°=y+ z 240=2z+52 146°=y 240- 52=2z
188=2z
188:2=z
94°=z
probă: x+ y+ z=360
120+146+ 94=360
266+ 94=360
360=360
O₂= y
O₃= z
O₄= w
x=2y- 61
y=3z+ 2
w=2z- 5
______________________
z= ? , y= ? , z= ? , w= ?
x=2y- 61 y=3z+ 2 w=2z- 5
x=2(3z+ 2)- 61
x+ y+ z+ w= 360
[2(3z+ 2)- 61]+ (3z+ 2)+z+(2z- 5)= 360
6z+ 4- 61+3z+ 2+z+ 2z- 5=360
12z-60=360
12z =360+ 60
12z =420
z =420:12
z = 35°
y=3z+ 2 x=2(3z+ 2)- 61 w=2z- 5
y=3·35+ 2 x=2(3·35+ 2)- 61 w=2·35- 5
y=105+ 2 x=2(105+ 2)- 61 w=70- 5
y= 107° x=2·107- 61 w= 65°
x=214- 61
x=153°
probă: x+ y+ z+ w=360
153+107+ 35+ 65=360
260+100=360
360=360
b.Notez: O₁= x
O₂= y
O₃= z
x=(y+ z): 2
z= y- 52
______________________
z= ? , y= ? , z= ?
x=(y+ z): 2 z= y- 52
2x=y+ z z+52= y
x+ y+ z= 360
x+ 2x = 360
3x =360
x =360: 3
x = 120°
2x=y+ z 240°=y+ z z+52= y
2·120= y+z 240=z+ 52+ z 94+52=y
240°=y+ z 240=2z+52 146°=y 240- 52=2z
188=2z
188:2=z
94°=z
probă: x+ y+ z=360
120+146+ 94=360
266+ 94=360
360=360
2) o1+o2+o3=180°
o1=(o2+o3):2
o3=o2-52°
o1=(o2+o2-52):2=(2o2-52):2=o2-26
o2-26+o2+o2-52=180
3o2-78=180
3o2=180+78=258
o2=258:3=86
o1=86-26=60
o3=86-52=34
o1=(o2+o3):2
o3=o2-52°
o1=(o2+o2-52):2=(2o2-52):2=o2-26
o2-26+o2+o2-52=180
3o2-78=180
3o2=180+78=258
o2=258:3=86
o1=86-26=60
o3=86-52=34