Answer :
The triangle MBF is isosceles triangle, because MB is congruent to MF
So, mAnd we should know that , the sum of the angles of the triangle = 180
So,
So,

The triangle MBF is isosceles triangle, because MB is congruent to MF
So, mAnd we should know that , the sum of the angles of the triangle = 180
So,
So,