Question 1208365
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In triangle ABC, the sum of the three angle measures is 180 degrees, so the sum of the measures of angles A and B is less than 180.<br>
In triangle AOB, angle OAB is half of angle A and angle OBA is half of angle B; therefore, the sum of the measures of angles OAB and OBA is less than 90 degrees.<br>
Angle AOB is the third angle in triangle AOB; since the sum of the measures in that triangle is 180 degrees, the measure of angle AOB is greater than 90 degrees.<br>
PROVED<br>