Curated OER
Angle Relationships
Students investigate geometric relationship using conjecture about linear pairs and vertical angles. In this geometry lesson, students apply their theorems and previous geometry knowledge to solve for and find angles of linear...
Curated OER
Angle Relationships
Tenth graders explore the angle relationships that exist when two lines intersect. In this geometry lesson, 10th graders estimate the measure of given angles and use their graphing calculator tools. Students use this knowledge to find...
EngageNY
Secant Angle Theorem, Exterior Case
It doesn't matter whether secant lines intersect inside or outside the circle, right? Scholars extend concepts from the previous activity to investigate angles created by secant lines that intersect at a point exterior to the...
EngageNY
Solve for Unknown Angles—Angles and Lines at a Point
How do you solve for an unknown angle? In this sixth installment of a 36-part series, young mathematicians use concepts learned in middle school geometry to set up and solve linear equations to find angle measures.
EngageNY
The Angle Measure of an Arc
How do you find the measure of an arc? Learners first review relationships between central and inscribed angles. They then investigate the relationship between these angles and their intercepted arcs to extend the Inscribed Angle Theorem...
EngageNY
Angle Problems and Solving Equations
Learners build connections between algebra and geometry as they study equation solving. The ninth instructional activity in the series of 28 asks pupils to write equations using angle relationships. After writing equations to model...
Texas Instruments
Identifying a Triangle by its Sides and Angles
Identify triangles by their angle measures and side lengths by looking at and measuring angle measures and side lengths. Use Cabri Jr. to construct various triangles, then manipulate the construction to create the 6 types of triangles,...
EngageNY
Similarity and the Angle Bisector Theorem
Identifying and verifying reproducible patterns in mathematics is an essential skill. Mathematicians identify the relationship of sides when an angle is bisected in a triangle. Once the pupils determine the relationship, they prove it to...
Virginia Department of Education
Lines and Angles
Explore angle relationships associated with transversals. Pupils construct parallel lines with a transversal and find the measures of the angles formed. They figure out how the different angles are related before constructing...
Curated OER
Supplementary, Complementary, and Vertical Angles
By using circles that they cut out and label themselves, learners literally "get a grip" on the angles they identify: supplementary, complementary, and vertical. They solve missing measurements based on properties of supplementary,...
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...
Alabama Learning Exchange
Origami Geometry
Origami is an excellent way to combine Japanese culture, art, and geometric shapes into one engaging instructional activity! Scholars begin by listening to the story Sadako and the Thousand Paper Cranes and learn the origin of...
EngageNY
Unknown Angle Problems with Inscribed Angles in Circles
We know theorems about circles—now what? Class members prove a theorem, with half the class taking the case where a point is inside the circle and half the class taking the case where a point is outside the circle. The activity then...
EngageNY
Sine and Cosine of Complementary Angles and Special Angles
Building trigonometric basics here will last a mathematical lifetime. Learners expand on the previous lesson in a 36-part series by examining relationships between the sine and cosine of complementary angles. They also review the...
EngageNY
Unknown Angle Proofs—Proofs with Constructions
Provide your emerging mathematicians with the tools to learn as they incorporate auxiliary lines to solve unknown angle proofs in this continuing segment. They decipher information from a diagram to uncover the missing pieces and...
West Contra Costa Unified School District
Arcs and Angles
Noah didn't construct this kind of arc. High school scholars first explore how angles can be formed in circles. They then learn relationships between angles and arcs by conducting an exploratory activity where they position and draw arcs...
Curated OER
Geometry Challenge
Students explore angle relationships and measure angles with a protractor by hand and online. They explore various websites and complete online activities and complete a worksheet.
Virginia Department of Education
Angles, Arcs, and Segments in Circles
Investigate relationships between angles, arcs, and segments in circles. Pupils use geometry software to discover the relationships between angles, arcs, and segments associated with circles. Class members use similar triangles to...
Curated OER
Hypatia: Angles
Introduce your young geometers to Hypatia, the first noted Greek female mathematician, and the properties of angles. Though this resource is missing worksheets that are needed to complete the lesson, the structure is sound and learning...
Curated OER
Geometry: Lesson 8
Eighth graders engage in a lesson that is concerned with the finding of angles that are found in different two dimensional figures. They compare and contrast exterior and interior angles while also determining the unknown measures of...
Curated OER
Quilting Geometry
Study geometry through the concept of quilt design. High schoolers examine the geometric shapes in various quilts and then create their own quilts using geometric shapes that fit together. In the end, they write a paragraph to...
Curated OER
Geometric Angles
Students explore angles and their use in Geometry. Students investigate three different kinds of angles: obtuse, acute, and right angles through an online activity. They identify pairs of angles with special relationships: vertical,...
Curated OER
Angles and Transversals
Pupils explore the concept of angles and transversals. They construct parallel and non-parallel lines cut by a transversal using Cabri Jr. Learners then determine which angles are congruent and the relationship of angles when two lines...
Curated OER
Measuring Angles in a Quadrilateral
High schoolers explore quadrilaterals in this geometry lesson. They will draw a quadrilateral, measure the angles, and find the sum of the measures of the interior angles using Cabri Jr. The interactive capabilities of Cabri Jr. allow...