Mathed Up!
Angles in Triangles and Quadrilaterals
This short video show viewers how to connect the sum of the angles in a triangle to other angle measurements. Pupils determine the missing measures for angles involved with triangles and quadrilaterals. Class members then must explain...
Illustrative Mathematics
Find the Missing Angle
This one activity requires young geometers to pull together information they are currently learning with things they have learned previously. Here they rely on understanding something about parallel lines, alternative interior angles,...
Mathed Up!
Angles: Parallel Lines
Viewers are presented with seven problems with parallel lines and angle relationships and must use the given information to find the measures of specific angles. To finish, they explain their process in finding the measures in the...
EngageNY
Law of Sines
Prove the Law of Sines two ways. The ninth segment in a series of 16 introduces the Law of Sines to help the class find lengths of sides in oblique triangles. Pupils develop a proof of the Law of Sines by drawing an altitude and a second...
EngageNY
More About Similar Triangles
Determine whether two triangles are similar. The lesson presents opportunities for pupils to find the criterion needed to show that two triangles are similar. Scholars use the definition of similarity to find any missing side...
Mathematics Assessment Project
Hopewell Geometry
Right triangles from 2,000 years ago? Learners investigate different right triangles found in the earthworks of the Hopewell people, a Native American culture that populated the United States from 200BC to AD 500. Learners apply concepts...
Mathed Up!
Sine and Cosine Rules and Area of Triangles
Learners discover how to find missing sides and angles using trigonometry. Scholars first watch a video covering the Law of Sines and Cosines, as well as the area formula for a triangle. To test their knowledge, they complete a worksheet...
EngageNY
Putting the Law of Cosines and the Law of Sines to Use
Use the Law of Cosines and the Law of Sines to solve problems using the sums of vectors. Pupils work on several different types of real-world problems that can be modeled using triangles with three known measurements. In the process,...
Inside Mathematics
Hopewell Geometry
The Hopewell people of the central Ohio Valley used right triangles in the construction of earthworks. Pupils use the Pythagorean Theorem to determine missing dimensions of right triangles used by the Hopewell people. The assessment task...
Mathed Up!
Trigonometry
Learn how to solve a triangle. Young mathematicians view a video that explains how to apply trigonometry to find missing sides and angles of a right triangle. A worksheet tests their understanding of the concept.
EngageNY
End-of-Module Assessment Task - Grade 8 Mathematics (Module 2)
Can your classes apply the knowledge they have learned? Use this performance task to find out! Individuals use transformations to explain congruence and angle relationships within parallel lines to find missing values. They show what...
Khan Academy
Khan Academy: Find Angles in Triangles
Find missing angle measures using the properties of triangles. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video, or receive hints.
Khan Academy
Khan Academy: Find Angles in Isosceles Triangles
Find missing angles in isosceles triangles given just one angle. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Find Angles in Congruent Triangles
Given two triangles, determine whether they are congruent and use that to find missing angle measures. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Find Angles in Congruent Triangles
Given two triangles, determine whether they are congruent and use that to find missing angle measures.
Khan Academy
Khan Academy: Solve Triangles: Angle Bisector Theorem
Use the Angle Bisector Theorem to find missing side lengths in triangles. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Solve Triangles: Angle Bisector Theorem
Use the angle bisector theorem to find missing side lengths in triangles.