Find the measure of the angle
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Find the measure of the angle
Let's remember that the sum of angles in a triangle is equal to 180 degrees.
Therefore, we will use the following formula:
Now let's input the known data:
We'll move the term to the other side and keep the appropriate sign:
88
Is DE side in one of the triangles?
This is a fundamental property of triangles in flat (Euclidean) geometry. No matter what shape or size triangle you have, the three interior angles will always sum to exactly 180°!
Check your arithmetic! Angles in a triangle are always positive. If you get negative, you likely made a calculation error or the given angles don't form a valid triangle.
No! The sum of any two angles must be less than 180°. In this problem, 69° + 23° = 92°, which is less than 180°, so it works.
Look at the diagram carefully! is marked at vertex A (the top point). The other angles are labeled with their degree measures: 69° and 23°.
Remember it this way: A triangle has 3 angles, and they always add to 180°. You can write it as or .
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