The Triangle Angle Sum Theorem states that the sum of the angles in a triangle is always 180 degrees. To find the measure of the third angle, you can use the formula:
\[ \text{Third angle} = 180° - (\text{First angle} + \text{Second angle}) \]
Here, the values are 34.6° and 52.8°.
First, calculate the sum of the two given angles:
\[ 34.6° + 52.8° = 87.4° \]
Now, subtract this sum from 180° to find the third angle:
\[ \text{Third angle} = 180° - 87.4° = 92.6° \]
So, the measure of the third angle is 92.6°.