Illustrative Mathematics
Sum of Angles in a Polygon
How can learners use algebra to solve a geometry problem? Help learners create an equation that shows the relationship between the number of sides of a polygon and the sum of the interior angles. Learners are asked to divide the...
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...
Scholastic
Study Jams! Area of a Triangle
Even though there is a wide variety of different triangles in the world, knowing a single equation allows us to find the area of each and every one of them. Follow along with this step-by-step presentation as Zoe clearly models how to...
Mathed Up!
Angles in Polygons
Show your class that finding angle measures is a regular calculation with a resource that provides 12 problems dealing with the measures of angles in regular polygons. Pupils use formulas for the sum of measures of angles in a polygon to...
Charleston School District
Parallel Lines Cut by a Transversal
Pupils study angle measurements between different types of angles associated with parallel lines and transversals. The independent practice asks pupils to identify the types of angles in a diagram and to determine the measure of...
EngageNY
Conditions on Measurements That Determine a Triangle
Can any three side lengths create a triangle? Your classes tackle this question and more in the 11th lesson of the 29-part module. Through modeling with patty paper, individuals discover the relationship between the lengths of the sides...
CK-12 Foundation
Pythagorean Theorem for Solving Right Triangles: Solving the Triangle
Observe the change in the trigonometric ratios as angles vary. An interactive provides the values of trigonometric ratios for both acute angles in a right triangle. Pupils create a right triangle to match given criteria and find the...
Alabama Learning Exchange
Triangle Congruence with Rigid Motion
Combine transformations and triangle congruence in a single activity. Scholars learn to view congruent triangles as a rigid transformation. Using triangle congruence criteria, learners identify congruent triangles and the rigid...
Corbett Maths
Constructing ASA Triangles
The narrator of a short video explains the steps in constructing a triangle given the measure of two angles and the length of the side between the angles. The resource provides opportunities for pupils to practice the skill with two...
EngageNY
Special Triangles and the Unit Circle
Calculate exact trigonometric values using the angles of special right triangles. Beginning with a review of the unit circle and trigonometric functions, class members use their knowledge of special right triangles to find the value...
EngageNY
Conditions for a Unique Triangle—Two Angles and a Given Side
Using patty paper, classes determine that only one triangle is possible when given two specific angle measures and a side length. As the 10th instructional activity in the series of 29, young math scholars add these criteria to those...
Corbett Maths
Hexagon Inscribed Within a Circle
Mark off the length of the radius around the circle. Using a compass, the presenter shows how to construct a regular hexagon in a circle. Pupils see how triangles formed in the hexagon are equilateral, allowing for the construction to...
EngageNY
An Area Formula for Triangles
Use a triangle area formula that works when the height is unknown. The eighth installment in a 16-part series on trigonometry revisits the trigonometric triangle area formula that previously was shown to work with the acute triangles....
CK-12 Foundation
Angles of Elevation and Depression: Fly-By Calibration
Determine the distance between two trees from afar. Pupils use an interactive resource to create two right triangles using trees and a plane. They determine the horizontal legs of each triangle to find the distance between the two trees.
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...
CK-12 Foundation
Angle-Angle-Side Triangles: Garden Gate
Good fences make good gardens. Individuals use an interactive to see how angles and sides relate in a triangular-shaped garden fence. They apply the Law of Sines to find the length of the garden gate (third side of triangle) given two...
Flipped Math
Unit 3 Review: Parallell and Perpendicular Lines
Learners watch a quick review on the Parallel and Perpendicular Lines unit. The pupils work through ten review problems ranging from identifying types of angles formed by parallel lines and transversals to writing equations of parallel...
EngageNY
Copy and Bisect an Angle
More constructions! In this third installment of a 36-part series, learners watch a YouTube video on creating door trim to see how to bisect an angle. They then investigate how to copy an angle by ordering a given list of steps.
CK-12 Foundation
Reference Angles and Angles in the Unit Circle: Exploring Reference Angles
A steal of a deal — get four angles for the value of one. An interactive resource allows individuals to visualize all four angles that have the same reference angle. Pupils answer questions by using the interactive to create the...
EngageNY
Conditions for a Unique Triangle—Three Sides and Two Sides and the Included Angle
Building on the previous lesson in the 29-part series, the ninth lesson asks individuals to construct a triangle given specific criteria. First, they are given three specific side lengths, followed by two sides and the included angle....
Flipped Math
Reference Triangles
It is all about where the side is located. Pupils use their knowledge of angles in standard position to find reference angles. They use the Pythagorean Theorem to find lengths along a terminal side of an angle to determine the exact...
Illustrative Mathematics
Base and Height
It is easy to find the area of a triangle where the base and the height are given. But in this resource, it is up to your geometers to identify the base and height of the triangle. In fact, your pupils will learn that there are three...
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...
Virginia Department of Education
Classifying Angles
Don't be obtuse, this geometry unit is the just the right resource for educating the acute young minds in your class. From classifying and measuring angles, to determining the congruence of shapes, this...