EngageNY
Ptolemy's Theorem
Everyone's heard of Pythagoras, but who's Ptolemy? Learners test Ptolemy's Theorem using a specific cyclic quadrilateral and a ruler in the 22nd installment of a 23-part module. They then work through a proof of the theorem.
Concord Consortium
Always, Sometimes, Never
Do your learners always, sometimes, or never remember the properties of the segments in triangles? Get that number closer to always with a creative lesson analyzing all four segments. Scholars consider a statement about one of the...
Curated OER
Inequalities
In this inequalities activity, 10th graders solve and complete 23 various types of problems. First, they find the area of an inscribed square in a circle shown. Then, students find the total area of the inscribed polygon and deduce...
National Council of Teachers of Mathematics
Improving Archimedes' Method
For this Archmides' method instructional activity, students determine the area of a regular n-gon inscribed in a circle. They use sine and cosine functions to solve problems. This three-page instructional activity contains 4 multi-step...
Curated OER
The Overlooked Regular Pentagon
Tenth graders discuss the history of geometry as it relates to pentagons. In this geometry lesson, 10th graders solve problems of a pentagon inscribed inside of a circle using ratio. They review other properties for shapes of polygons...
Curated OER
Inscribed Right Triangles
Learners calculate the measurements of the inscribed angles of a triangle. For this geometry lesson, students relate the hypotenuse of a right triangle and the diameter of a circle to each other. They calculate the diameter of a circle...
Curated OER
Geometry: Basic Constructions
For this geometry worksheet, 10th graders use a straightedge and a compass to construct congruent segments and angles, bisect a segment and an angle, construct perpendicular and parallel lines, construct tangents, circumscribe a circle...
Curated OER
Triangles with Collinear Circumcenters
Students identify the circumcenter of a triangle. In this geometry lesson, students construct a perpendicular bisector using a straight edge and a compass. They differentiate between triangles and collinear points.
Curated OER
Regents Exam Questions G.G.21: Centroid, Orthocenter, Incenter, and Circumcenter
In this triangles worksheet, high schoolers solve 4 multiple choice problems. Students find the centroid, orthocenter, incenter, and circumcenter or various triangles.
Virginia Department of Education
High School Mathematics Geometry Vocabulary Word Wall Cards
Having a good working knowledge of math vocabulary is especially important for geometry learners. Here are 119 pages worth of wonderfully constructed definitions, constructions, formulas, properties, theorems, and postulates. This is a...
EngageNY
Cyclic Quadrilaterals
What does it mean for a quadrilateral to be cyclic? Mathematicians first learn what it means for a quadrilateral to be cyclic. They then investigate angle measures and area in such a quadrilateral.
Curated OER
Triangles
In this triangles worksheet, 10th graders solve 3 extensive informal geometry problems that involve triangles. First, they sketch a triangle, selecting 3 of the sides and constructing 3 midpoints. Students then draw each of 3 medians by...
Curated OER
Creating a Cyclic Quadrilateral
Identify and make conjecture about properties of cyclic quadrilaterals. Students use the TI Navigator to create different shapes and draw conclusions.
Illustrative Mathematics
Placing a Fire Hydrant
Triangle centers and the segments that create them easily become an exercise in memorization, without the help of engaging applications like this lesson. Here the class investigates the measure of center that is equidistant to the three...
EngageNY
End-of-Module Assessment Task: Pre-Calculus Module 4
Challenge your scholars to show what they know about the Law of Sines, Law of Cosines, and inverses. The six-question assessment is the last in a series of 16. Pupils find the area of triangles and show that the Law of Sines and Law of...
Curated OER
Areas of Polygons
Students calculate the are of regular polygons. In this geometry instructional activity, students create polygons on the computer and move it around to create different shapes. They explore the area of different polygons and how they...
Curated OER
"Sir Cumference and the First Round Table" by Cindy Neuschwander
Students analyze characteristics of various 2 dimensional shapes and explore their properties and use various vocabulary terms to discuss geometric relationships.
Curated OER
Special Segments is a Triangle
In this geometry learning exercise, 10th graders examine the special segments that occur in a triangle. The three page learning exercise contains twenty-five problems. Answers are not included.
Curated OER
Pape's Theorems
In this math worksheet, learners find the length of the side of a regular hexagon whose area is numerically equal to its perimeter.
Curated OER
Infinite Secrets
Students duplicate the method that Archimedes used to estimate the value of pi. They complete a data table and find the approximate values of pi for three sets of polygons.
Curated OER
Proposed Problems
In this math worksheet, pupils read the information about an isosceles triangle. The ratio of the lengths of two sides is equal. They determine the exact measures of its angles.