1) Сумма внутренних углов четырехугольника равна 360°
4x + 5x + 7x + 20x = 360
36x = 360
x = 10
4x = 40° 5x = 50° 7x = 70° 20x = 200°
2) a = 160°
c = b + 34° => b = c - 34
c = 2d => d = c/2
a + b + c + d = 360
160 + (c - 34) + c + c/2 = 360
2,5c = 234
c = 93,6°
b = 93,6 - 34 = 59,6°
d = 93,6 : 2 = 46,8°
a + b + c + d = 160 + 59,6 + 93,6 +46,8 = 360