Curated OER
Triangle's Interior Angles
Given a pair of parallel lines and a triangle in between, geometers prove that the sum of the interior angles is 180 degrees. This quick quest can be used as a pop quiz or exit ticket for your geometry class.
EngageNY
Angle Sum of a Triangle
Prove the Angle Sum Theorem of a triangle using parallel line and transversal angle relationships. Pupils create a triangle from parallel lines and transversals. They find angle measures to show that the angles of a triangle must total...
Willow Tree
Angle Sum Property of Triangles
All triangles have some things in common. Using these properties of triangles, learners find missing angle measures. Scholars use the Angle Sum Property and properties of special triangles throughout the instructional activity.
Curated OER
Angle Sum of Triangles and Quadrilaterals
In this angle sum instructional activity, students find missing angles of 20 triangles and quadrilaterals. Students find the missing angle in each polygon by using the total degrees of each and given angle measures.
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. Students are asked to divide the...
Hotchalk
Triangle Sum Theorem
Your visual geometry learners will appreciate triangle drawings as they model the triangle sum theorem and algebraically solve to find the missing interior angle in a triangle. Practice problems increase in complexity and vary in their...
Curated OER
Geometry - Angles Overview
Learners address 14 questions that include naming all pairs of opposite and supplementary angles for sets of intersecting lines and then, finding the measure of the unknown angle. They determine the measure of the angle that is...
Illustrative Mathematics
Right Triangles Inscribed in Circles I
One of the basic properties of inscribed angles gets a triangle proof treatment in a short but detailed exercise. Leading directions take the learner through identifying characteristics of a circle and how they relate to angles and...
Mathematics Vision Project
Geometric Figures
Logical thinking is at the forefront of this jam-packed lesson, with young mathematicians not only investigating geometric concepts but also how they "know what they know". Through each activity and worksheet, learners wrestle with...
Charleston School District
The Sum of Angles in a Triangle
An informative lesson contains a brief explanation of how the sum of the angles of a triangle is a line. The lesson continues with determining the missing angle in a triangle, or solving for a variable. Using the sum of the angles, the...
Curated OER
Investigation - Adrienne's Pattern Block Angles
Fifth graders investigate possible solutions to a word problem. They explore properties of polygons and right angles. Students demonstrate proper angle measurement. Students discover patterns.
Willow Tree
Interior Angles, Exterior Angles, and Diagonals of Polygons
How does the number of sides of a polygon affect the angle measures? Learners recognize a pattern in finding the total measure of interior and exterior angles and the number of diagonals. They use the patterns to calculate the number of...
EngageNY
More on the Angles of a Triangle
Angles and triangles: they're all connected. Uncover the connections between angles in triangles. Scholars learn how to find both exterior and interior angle measures in triangles. The lesson emphasizes the vocabulary related to these...
EngageNY
Unknown Angle Proofs—Proofs of Known Facts
Lead the class in a Greek history lesson with a geometric twist. Pupils relate a short video about geometric properties to modern-day methods of solving for unknown angles. They discuss parallel line theorems and complete practice...
Curated OER
Exploring Characteristics of Triangles
Students draw triangles and explore the classification of each using the measures of interior angles and lengths of sides. They investigate the sum of the interior angles of various triangles and conjecture and prove the theorem: The...
Curated OER
Interior and Exterior Angles of Polygons
In this angles of polygons learning exercise, 10th graders solve and complete 18 different problems that include determining various interior and exterior angles. First, they determine the measure of various angles described in the first...
Curated OER
Properties of Angles, Lines, and Triangles
In this properties of angles, lines and triangles worksheet, 10th graders solve and complete 28 different problems that include determining the measurement of various figures shown. First, they use the geometric properties and theorems...
Curated OER
Finding the Sum of the Exterior and Interior Angles of a Polygon
Students find the sum of the angles of a polygon and construct a polygon given the number of sides. In this polygon lesson plan, students draw large polygons on the floor of the room. They measure the length of each side and the interior...
Curated OER
Triangle Similarity
In this triangle similarity worksheet, 10th graders solve and complete 12 different problems that include defining similar and 3 similar statements using only sides and angles. First, they determine if each pair of triangles shown are...
Curated OER
Triangle Classificaition with Geometer's Sketchpad.
Students use Geometer's Sketchpad to draw triangles and explore the classificaiton of each using the mearsures of interior angles and the lengths of the sides.
Curated OER
Sum of Angles on a Triangle
Use this lesson for a basic review of angles. While the activities discussed are outlined, there are no materials provided to make implementation possible. When using this resource, it is necessary to create worksheets and other...
Curated OER
Polygons
In this polygons worksheet, students read about and complete many activities involving triangles, angles, and symmetry. Students complete 17 pages of activities.
Curated OER
Triangle Inequality Theorem
Learners use the inequality theorem to solve triangles and their properties. In this geometry lesson, students are given spaghetti of different lengths and asked to create triangles. They conclude the necessary length needed to make a...
Curated OER
Applying Special Right Triangles
For this geometry worksheet, 10th graders use the theorems regarding right triangles to find the missing length in a special right triangle. The one page worksheet contains eleven questions. Answers are included.