Answers

2014-04-08T19:44:14+05:30
As the sidess AB=BC then the anglesBAC = angle BCA = 30degree

And external angle = 180 - (sum of the opposite interior angles)
                            = 180 - (30+30)
                            = 180 - 60
                            = 120 degrees

so the external angle B  = 120 degrees
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from where u got 30 , please tell ?
2014-04-08T20:11:03+05:30
He external b measures = 120°
1 5 1
but how , in the given option , there is no option with 120 ???