Question

Angle AOC=BOC =90 degrees prove that AOB is a line
This question is of class 9th

Answer 1

As  AOC and BOC have common arm  so BC is a straight line...as it forms 180 degree angle on it.Hence proved

Answer 2

Answer: given : aoc=boc=90

to prove : aob is a line or aob = 180

proof : aoc + boc = aob

           90 + 90= aob

           aob = 180 ( we know that a line is straight if its angle is 180 degrees)              

           hence proved.