Since triangle ABC is congruent to triangle DEF...
- angle A is congruent to angle D
- angle B is congruent to angle E
- angle C is congruent to angle F
Since angle B is congruentto angle E, and since angle E is 25 degrees, we can say that the measure of angle B is also 25 degrees.
The angle measures of a triangle sum to 180 degrees, so we can subtract the two given angle measures from 180.
180-55-25=100
Therefore, the measure of angle C is 100 degrees.
