A right triangle ABC is given, where angle B = 90 degrees. The side AB is extended past angle B so that an exterior angle X is formed. What is the measure in degrees of angle X? 45 DEGREES 55 DEGREES 180 DEGREES 90 DEGREES 50 DEGREES
Makes sense: draw rt angle triangle: point b vertically below a and point c horizontally across from b (angle B = 90). Now continue line ab thru point b. The angle between that line and the triangle base is 90.
It's also a (reasonably) well-known mathematical proof that the exterior angle is equal to the sum of the other two interior angles of the triangle, which also gives us 90 degrees as the answer.