Question

Please solve the above problem. Thanks in advance

Answer 1

If We Extend the both sides of side BC, we get Two Exterior Angles one on each side of B and C.

The Exterior Angle of the Vertex B is 180 - Angle(B)

The Exterior Angle of the Vertex C is 180 -Angle(C)

The Sum of Exterior Angles of side BC is 360 - Angle(B + C)

We know that Sum of Angles in a Triangle is = 180 that is A+B+C=180

From the Above we can say that B+C= 180 - A

So, The sum of the Exterior angles of Side BC is 360 - 180 + A = 180 + A

From the above we can say that the Difference between the Sum of Exterior Angles of BC and Angle A is 180 that is Two Right angles.