Solve for Unknown Angles — Angles in a Triangle
Find the measure of angle 𝑥 in the figure to the right. Explain your calculations. (Hint: Draw an auxiliary line segment.)
The sum of the 3 angle measures of any triangle is ______.
INTERIOR OF A TRIANGLE: A point lies in the interior of a triangle if it lies in the interior of each of the angles of the triangle.
In any triangle, the measure of the exterior angle is equal to the sum of the measures of the ____ angles. These are sometimes also known as ____ angles. Base angles of an ____ triangle are equal in measure. Each angle of an ____ triangle has a measure equal to 60°.
ISOSCELES TRIANGLE: An isosceles triangle is a triangle with at least two sides of equal length.
ANGLES OF A TRIANGLE: Every triangle △ 𝐴𝐵𝐶 determines three angles, namely, ∠𝐵𝐴𝐶, ∠𝐴𝐵𝐶, and ∠𝐴𝐶𝐵. These are called the angles of △ 𝐴𝐵𝐶.
EXTERIOR ANGLE OF A TRIANGLE: Let ∠𝐴𝐵𝐶 be an interior angle of a triangle △ 𝐴𝐵𝐶, and let 𝐷 be a point on ⃡𝐴𝐵 such that 𝐵 is between 𝐴 and 𝐷. Then ∠𝐶𝐵𝐷 is an exterior angle of the triangle △ 𝐴𝐵𝐶.
Try the free Mathway calculator and
problem solver below to practice various math topics. Try the given examples, or type in your own
problem and check your answer with the step-by-step explanations.
We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.