https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-geometry/cc-8th-angles-between-lines/v/using-algebra-to-find-measures-of-angles-formed-from-transversal 2025-06-10T12:18:12.264638758Z Measures of angles formed by a transversal When parallel lines are crossed by another line called a transversal, special angles are formed. We can find the measures of these angles using algebra and the relationships between the angles, like congruent angles and supplementary angles. Once we solve for the variable, we use that value to figure out the angle measures. Sal Khan video https://cdn.kastatic.org/googleusercontent/jH5ENXnD6D-PN3MBbpChj1DItsL6-IBBlBy4CSWjNhZisvLGEEEuEoyVVhW6tRAfsndWS8O7Q7v4u9lIu_ugTO9D Measures of angles formed by a transversal When parallel lines are crossed by another line called a transversal, special angles are formed. We can find the measures of these angles using algebra and the relationships between the angles, like congruent angles and supplementary angles. Once we solve for the variable, we use that value to figure out the angle measures. https://cdn.kastatic.org/ka-youtube-converted/Ld7Vxb5XV6A.mp4/Ld7Vxb5XV6A.mp4 281 Ángulos entre rectas que se intersectan https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-geometry/cc-8th-triangle-angles/v/triangle-angle-example-2 2023-06-02T19:09:07.369858129Z Worked example: Triangle angles (intersecting lines) Learn how to find unknown angles in triangles and intersecting lines. We use concepts like supplementary angles (angles that add up to 180°), vertical angles (opposite angles made by two crossing lines), and exterior angles (angles outside a triangle). There are lots of ways to think about this problem. Sal Khan video https://cdn.kastatic.org/googleusercontent/zGCHqinDWdb7VUFyJHlpvrcCfW_SjkBC1_ufAhF6ZiA9cRZUoXqIwEIpXHI_RdNUYD3l68G9LtVPPZuUkfjUcqA Worked example: Triangle angles (intersecting lines) Learn how to find unknown angles in triangles and intersecting lines. We use concepts like supplementary angles (angles that add up to 180°), vertical angles (opposite angles made by two crossing lines), and exterior angles (angles outside a triangle). There are lots of ways to think about this problem. https://cdn.kastatic.org/ka-youtube-converted/eTwnt4G5xE4.mp4/eTwnt4G5xE4.mp4 295 Ángulos entre rectas que se intersectan https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-geometry/cc-8th-triangle-angles/v/triangle-angle-example-3 2023-06-02T19:09:07.369858129Z Worked example: Triangle angles (diagram) We have a right triangle that's split into several smaller right triangles. The angle measures in any triangle always add up to 180 degrees. By using this fact and looking at complementary (adding up to 90 degrees) and supplementary (adding up to 180 degrees) angles, we can find the missing angle measures in the triangles. Sal Khan video https://cdn.kastatic.org/googleusercontent/o8ICTuKDwBsQ2PkEj-iWNEdxNrZgClsvpH1n894dLUVrbwhSxxAruyq7FeecsfnfL6j8l0CMmOtP0jkeiMbNvrs Worked example: Triangle angles (diagram) We have a right triangle that's split into several smaller right triangles. The angle measures in any triangle always add up to 180 degrees. By using this fact and looking at complementary (adding up to 90 degrees) and supplementary (adding up to 180 degrees) angles, we can find the missing angle measures in the triangles. https://cdn.kastatic.org/ka-youtube-converted/iqeGTtyzQ1I.mp4/iqeGTtyzQ1I.mp4 342 Ángulos entre rectas que se intersectan https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-geometry/cc-8th-triangle-angles/e/angles_2 2026-03-31T08:44:48.259988263Z Finding angle measures using triangles Use your knowledge about angles to find missing angle measures in various complex situations. David Lai exercise https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-geometry/cc-8th-triangle-angles/v/finding-more-angles 2023-06-02T19:09:07.369858129Z Triangle angle challenge problem 2 Find angle measures in triangles when the given measures are algebraic expressions. The key idea is that the sum of all angles in a triangle is always 180 degrees. We can also use parallel lines and transversals to find angle measures. Sal Khan video https://cdn.kastatic.org/googleusercontent/SVQhkWdZHtQhIhzAJ5GAIj4P77hsA3Zy0xclN-77OmMo60KSWLLH-P4AL5bO2bYznZPehE1BSRBXDuQ28E-_qfFxCg Triangle angle challenge problem 2 Find angle measures in triangles when the given measures are algebraic expressions. The key idea is that the sum of all angles in a triangle is always 180 degrees. We can also use parallel lines and transversals to find angle measures. https://cdn.kastatic.org/ka-youtube-converted/0gzSreH8nUI.mp4/0gzSreH8nUI.mp4 365 Ángulos entre rectas que se intersectan https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-geometry/cc-8th-triangle-angles/a/triangle-angles-review 2024-06-17T03:51:36.667583972Z Triangle angles review Review the basics of triangle angles, and then try some practice problems. article