Curated OER
Trig Cheat Sheet
Your pre-calculus learners will make use of this wonderful cheat sheet that summarizes all things trigonometric. Definitions based on both the unit circle and the right triangle are included, as well as many convenient trigonometric...
Concord Consortium
Line of Sight
There's no way around it—learners must use trigonometry to model the line of sight around a race track! Using the starting line as the origin, pupils model the straight line distance to any car using a trigonometric expression. The...
Mathematics Vision Project
Module 7: Modeling with Geometry
Model good modeling practices. Young mathematicians first learn about cross sections and solids of revolution. They then turn their attention to special right triangles and to the Laws of Sine and Cosine.
Yummy Math
Parametric Equations and a Heart
Trigonometry, art, and Valentine's Day come together in a creative activity about parametric equations. Learners calculate several equations before graphing them either by hand, on a graphic calculator, or Excel spreadsheet to curve...
Alabama Learning Exchange
Triangle Area: No Height? Use the Sine
No height? No problem! Learners use their knowledge and a little help from GeoGebra to develop the Law of Sines formula. The Law of Sines helps to determine the height of triangles to calculate the area.
CK-12 Foundation
Determination of Unknown Triangle Measures Given Area: Jib Sheets
Solving triangles is a breeze. Young boat enthusiasts solve problems involving triangles in the context of sails on a boat. They must apply different strategies, including the Law of Cosines and area formulas.
Mathematics Assessment Project
Modeling Motion: Rolling Cups
Connect the size of a rolling cup to the size of circle it makes. Pupils view videos of cups of different sizes rolling in a circle. Using the videos and additional data, they attempt to determine a relationship between cup measurements...
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...
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....
Schoolcraft College
Trigonometry
This trigonometry textbook takes the learner from a basic understanding of angles and triangles through the use of polar coordinates on the complex plane. Written by a mathematician-engineer, examples and problems here are used to...
Illustrative Mathematics
Seven Circles III
A basic set-up leads to a surprisingly complex analysis in this variation on the question of surrounding a central circle with a ring of touching circles. Useful for putting trigonometric functions in a physical context, as well as...
Curated OER
Area Measures and Right Triangles
Your class will investigate the relationship among different triangles. This geometry lesson, demonstrates how to make a connection between triangles and the Pythagorean Theorem. They identify the missing side or angle of a triangle.
Texas Instruments
REAL LIFE REAL WORLD Activity - Surveyor
Learners investigate surveying in this secondary mathematics lesson. They will explore a real world application of geometry and trigonometry as they create a plot plan using a geometry utility and calculate the area of the land parcel.
Maths Challenge
Maths challenge.net: Sloping Square
A geometry problem of finding the area of a sloped square within a square.
Maths Challenge
Maths challenge.net: Triangle Area
Find the area of this triangle in a coordinate plane.
Maths Challenge
Maths challenge.net: Circumscribed Triangle
Find the area of this circumscribed triangle with your geometry skills.
Maths Challenge
Maths challenge.net: Triangle in a Square
A "three star" geometry problem requiring some prior knowledge in math and proofs to maximize the area of an inscribed triangle in terms of the hypotenuse.
That Quiz
That Quiz: Practice Test: Triangles
Test your knowledge on the attributes of triangles. There are eleven levels that may be completed with or without a timer.
Mathigon
Mathigon: Geometry: Triangles and Trigonometry: Properties of Triangles
This lesson focuses on the properties of triangles, a closed shape that has three sides, three vertices, and and three internal angles. There are different types of triangles such as a right triangle, obtuse, and acute based on the...
Cuemath
Cuemath: Median of a Triangle
This lesson explores the equation of the median of a triangle formula, sum of medians of a triangle, altitude of a triangle, median of equilateral triangle formula, and median of a triangle definition while discovering the interesting...
Cuemath
Cuemath: Midsegment of a Triangle
This mini-lesson explores the world of the midsegment of a triangle by finding the answers to questions like what is midsegment of a triangle, triangle midsegment theorem, and proof with the help of interactive questions.
Cuemath
Cuemath: Altitude of a Triangle
Explore the world of the altitude of a triangle in this mini-lesson including its definition, altitudes in different types of triangles, formulae, some solved examples, and a few interactive questions for you to test your understanding.
Wolfram Research
Wolfram Math World: Incenter
MathWorld diagrams triangle with its incenter labeled and details how to find the incenter with links to the key terms. The site details many other interesting properties of the triangle incenter.
Texas Instruments
Texas Instruments: Constructing Triangles
This activity focuses on the various ways to construct the different types of triangles such as isosceles, equilateral, right, and right isosceles triangles. Students will begin by constructing triangles based on a minimal definition of...