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....
CK-12 Foundation
Alternate Formula for the Area of a Triangle: Alternate Area of a Triangle
It's always nice to have a plan B. Pupils investigate an alternate formula for the area of a triangle that uses sine. A set of challenge questions shows how the new formula relates to the well-known formula of (1/2)bh.
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.
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.
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...
Mathed Up!
Sine and Cosine Rules and Area of Triangles
Learners discover how to find missing sides and angles using trigonometry. Scholars first watch a video covering the Law of Sines and Cosines, as well as the area formula for a triangle. To test their knowledge, they complete a learning...
Chapman University
A Pythagorean-Style Proof of the Sine Sum-of-Angles Formula
This well organized poster shows a step-by-step algebraic proof and related graphic. Understanding how formulas were derived, connects learners to the idea that the study of mathematics is continuous and cumulative. Learners will also...
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
Area of a Triangle
Students solve the area of triangles. For this precalculus lesson, students are given two sides of a triangle and asked to calculate the area. They apply the law of sine and the side-angle-side area formula to solve.
Curated OER
Law of Sines and Cosines
Students solve problems using sine and cosine. In this precalculus instructional activity, students apply the properties of sine and cosine to solve non-right triangle problems. They use Heron's Law to find the area of a shape.
Curated OER
Sine and Cosine
Students solve problems using sine and cosine. In this precalculus lesson, students solve word problems using sine and cosine. They identify where it is appropriate to laws of sine and cosine and where to use the Pythagorean Theorem.
Mathematics Vision Project
Module 5: Modeling with Geometry
Solids come in many shapes and sizes. Using geometry, scholars create two-dimensional cross-sections of various three-dimensional objects. They develop the lesson further by finding the volume of solids. The module then shifts to finding...
Curated OER
Law of Sine and Cosine
Students solve problems using the law of sine and cosine. In this precaclulus lesson, students learn the law of DeMoivre's Theorem and Heron's theorem. They use both theorems to solve problems.
Curated OER
Math Handbook: Trigonometry
You'll be spinning in unit circles once you read through this jumbo-sized resource of everything you need to know about trigonometry. Each page has color-coded examples with explicit directions that detail the problems and formulas.
Curated OER
The Law of Sines
Learners define the laws of sine as it relates to a right triangle. In this trigonometry lesson, students identify the properties of sine to help then find mixing sides of a right triangle. They also solve for the missing angles.
Curated OER
Section 6.1-6.2 Precalculus: Trigonometry
In this trigonometry instructional activity, students solve 15 triangle problems. Students use the law of sines and law of cosines to find the missing angles and side lengths of a triangles.
EngageNY
Complex Numbers and Transformations
Your learners combine their knowledge of real and imaginary numbers and matrices in an activity containing thirty lessons, two assessments (mid-module and end module), and their corresponding rubrics. Centered on complex numbers and...
Curated OER
Trigonometry Worksheet
For this trigonometry worksheet, students use the law of sines to find the length of a missing side of a triangle. They prove trigonometric identity and use Heron's formula to find the area of a triangle. This two-page worksheet...
Curated OER
Some More Trigonometry
Young scholars define the law of cosine and its correct usage. In this trigonometry lesson, students define the law of Heron's area formula and use it to solve problems. They review other trigonometric values and identify the identities.
Center for Innovation in Mathematics Teaching
Trigonometry
This unit covers the basic trigonometry including understanding radians, how to convert between radians and degrees, the area of a circle subtended by an angle, basic properties and graphs of sine, cosine, tangent, and solving...
Curated OER
Basic Theorems and Proofs
In this pre-calculus worksheet, 11th graders recall the three forms of the law of cosines and used it to solve problems involving triangles. They also write out the laws of sines and use those to solve problems with angles. There are 15...
Curated OER
Geometry Exploration Basic Trig Functions
Tenth graders solve for missing sides on a triangle using the Pythagorean Theorem. In this geometry lesson, 10th graders are introduced to basic trigonometry functions as they solve problems of right triangles. They discuss the formulas...
Curated OER
Law of Cosines
Young scholars model scenarios using functions and their properties. For this trigonometry lesson, students calculate the angles of sine, cosine and tangent. They perform operation using a calculator.
Curated OER
Sled Kites and Trigonometry
Pupils study the history of kites and their fundamental properties. In this kites lesson students divide into teams and build and fly kites.