Apply the triangle angle sum theorem, exterior angle theorem, and triangle inequality.
Triangle Angle Sum: The three interior angles of ANY triangle sum to 180°. [formula] Exterior Angle Theorem: An exterior angle of a triangle equals the sum of the two non-adjacent interior angles. [formula] Triangle Inequality: The sum of any two sides must be greater than the third side. [formula]
Example: A triangle has angles 50°, 65°, and x°. Find x.
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