In triangle ABC, angle C is 55 AD – bisector of angle A, angle ADB is 70 find the degree measure of angle B.

The angles ADC and ADB are adjacent angles, the sum of which is 180, then the angle ADC = (180 – ADB) = (180 – 70) = 110.

In the triangle ACD, define the value of the angle CAD.

Angle CAD = (180 – ACD – ADC) = (180 – 55 – 110) = 15.

Since, by condition, AD is the bisector of the CAB angle, the CAB angle = 2 * CAD = 2 * 15 = 30.

Then in the triangle ABC we determine the value of the angle ABC.

Angle ABC = (180 – 55 – 30) = 95.

Answer: The angle B is 95.