In Fig. 6.16, if x + y = w + z, then prove that AOB is a line.


It is given in the question that:

x + y = w + z


To prove,


AOB is a line or x + y = 180o (Linear pair)


Now, according to the question,


x + y + w + z = 360o (Angles at a point)


(x + y) + (w + z) = 360o


(x + y) + (x + y) = 360o (Given, x + y = w + z)


2 (x + y) = 360o


(x + y) = 180o


Therefore, x + y makes a linear pair.


And, AOB is a straight line


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