Final answer:
The measure of the third angle is 99 degrees.
Step-by-step explanation:
In a triangle, the sum of all three angles is always 180 degrees. Given that two angles already add up to 81 degrees, we can find the measure of the third angle by subtracting the sum of the given angles from 180 degrees.
Therefore, the measure of the third angle is 99 degrees.
Answer: 99 degrees
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