Question

prove that the internal and external bisectors of an angle are perpernpendicular to each other
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Answer 1

Answer:

LEMMA: The internal and external bisectors of at an angle of a triangle are perpendicular. Proof: The sum of the internal angle and the external angle is 180 degrees. The angle between the internal and external bisectors is the sum of one-half of each. Therefore the angle measures 90 degrees.