Virginia Department of Education
Special Right Triangles and Right Triangle Trigonometry
Right triangles are so special! Use special right triangles to discover the trigonometric ratios. Pairs construct special right triangles and find the values of the ratios of the sides. In the process, they discover the ratios stay the...
Curated OER
Special Right Triangles
In this special right triangle worksheet, students use the trigonometric functions to determine angle measurement or the length of one side of a right triangle. This one-page worksheet contains 18 problems. Answers are provided at the...
Curated OER
Trigonometric Functions of Acute Right Triangles
Students derive the six trigonometric functions. In this trigonometry activity, students show their understanding of trigonometric functions as they relate the right triangles. They find the missing angles and side use trig ratios of...
Curated OER
Ratios in Right Triangles
Learners calculate the sides of right triangles in this trigonometric ratios lesson. They use Cabri Jr. software and TI-83 or TI-84 calculators to find the side lengths and their ratios to each other for various triangles. The provided...
Curated OER
Finding the Area of an Equilateral Triangle
The problem seems simple: find the area of the equilateral triangle whose sides are each length 1. In fact, this same problem is solved in 8th grade, addressing a different Common Core standard, using the formula for area of a triangle...
EngageNY
From Circle-ometry to Trigonometry
Can you use triangles to create a circle? Learners develop the unit circle using right triangle trigonometry. They then use the unit circle to evaluate common sine and cosine values.
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 of...
EngageNY
The Converse of the Pythagorean Theorem
Is it a right triangle or not? Introduce scholars to the converse of the Pythagorean Theorem with a lesson that also provides a proof by contradiction of the converse. Pupils use the converse to determine whether triangles with given...
Curated OER
Right Triangles and The Unit Circle
Students solve right triangles using trigonometry. In this geometry lesson, students use the unit circle to identify different trig values. They identify the six trigonometric identities.
Curated OER
Right Triangles and The Pythagorean Theorem
Students play a game to reinforce concepts of the Pythagorean Theorem. In this geometry lesson, students find the missing angle and lengths of a right triangle. They use properties of trigonometry about sine, cosine and tangent to solve...
Curated OER
Solving Right Triangles
Students investigate the basic trigonometric functions. In this geometry/trigonometry lesson, students explore strategies to solve right triangles using basic trigonometric functions. The lesson includes an application problem in which...
EngageNY
Unknown Angles
How do you solve an equation like trigonometry? Learners apply their understanding of trigonometric ratios to find unknown angles in right triangles. They learn the meaning of arcsine, arccosine, and arctangent. Problems include basic...
Illustrative Mathematics
Two Wheels and a Belt
Geometry gets an engineering treatment in an exercise involving a belt wrapped around two wheels of different dimensions. Along with the wheels, this belt problem connects concepts of right triangles, tangent lines, arc length, and...
EngageNY
Trigonometry and the Pythagorean Theorem
Ancient Egyptians sure knew their trigonometry! Pupils learn how the pyramid architects applied right triangle trigonometry. When comparing the Pythagorean theorem to the trigonometric ratios, they learn an important connection that...
Curated OER
Right Triangles and Unit Circles
Pupils evaluate the six trigonometric values of a trig function. In this trigonometry lesson, students use the Unit Circle to find the values of right triangles and their angles. They identify an angle of elevation and depression.
Texas Instruments
What's the Trig?
Learners determine the trigonometric relationships within a triangle as they construct a right triangle on the Ti-89. They find the sine, cosine, and tangent of various angles of their triangle construction.
EngageNY
Incredibly Useful Ratios
Start the exploration of trigonometry off right! Pupils build on their understanding of similarity in this lesson plan that introduces the three trigonometric ratios. They first learn to identify opposite and adjacent...
EngageNY
Using Trigonometry to Find Side Lengths of an Acute Triangle
Not all triangles are right! Pupils learn to tackle non-right triangles using the Law of Sines and Law of Cosines. After using the two laws, they then apply them to word problems.
EngageNY
Proof of the Pythagorean Theorem
What does similarity have to do with the Pythagorean Theorem? The activity steps through the proof of the Pythagorean Theorem by using similar triangles. Next, the teacher leads a discussion of the proof and follows it by an animated...
EngageNY
Using Trigonometry to Determine Area
What do you do when you don't think you have enough information? You look for another way to do the problem! Pupils combine what they know about finding the area of a triangle and trigonometry to determine triangle area when they don't...
Curated OER
Introduction to Trigonometry
Young scholars identify the six trigonometric ratios and properties. In this trig lesson plan, students define basic trig functions as it relates to solving right triangles. They identify the equation for sine as o/h and cosine as a/h...
Curated OER
Applications of Triangles
Students apply the properties of a right triangle. In this triangle lesson, students describe and compare radians to degrees. They solve problems using the properties and ratios of a right triangle.
Curated OER
Concepts in Precalculus 1: Trigonometry
Learners investigate trigonometry. In this Algebra II/Pre-calculus/Trigonometry lesson, students explore Islamic achievements in mathematics as they calculate angles and distances using the Law of Sines and the Law of Cosines. ...
Curated OER
Basic Trigonometric Ratios
In this trigonometric ratio worksheet, learners determine the length of a side of a right triangle, or the measurement of angles using trigonometric ratios. This one-page worksheet contains 24 problems. Answers are provided at the bottom...