In Fig. 5.28, PQ || RS. If 1 = (2a + b)° and 6 = (3a–b)°, then the measure of 2 in terms of b is


1 = (2a + b)° …Equation (i)


6 = (3a–b)°


Since 5 and 6 forms a linear pair so


5 = (180-3a + b)°


5 = 1 = (180-3a + b)° (Corresponding angles) …Equation (ii)


Equating Equation (i) and Equation (ii) we get


2a + b = 180-3a + b


5a = 180


a = 360


Since 1 and 2 forms a linear pair so


2 = 1800- 2a-b


2 = (108-b)0

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