Question

Explaination of question 4 in exercise 6.1

Answer 1

x+y = 180 degree
x+y+w+z = 360 degree
x+y+x+y = 360 degree [ because in question it is given that x+y = w+z]
2x+2y =360 degree
2( x+y) = 360 degree
x+y = 360/2
x+y = 180 degree
AOB is a straight line