Merriam-Webster
Merriam Webster: Dictionary Illustration: Types of Triangles
A labeled illustration of six different types of triangles.
Wolfram Research
Wolfram Math World: Right Triangle
This site from MathWorld.com offers extensive information on right triangles. The site contains information on numerous characteristics of right triangles, including constructing similar inscribed triangles, altitudes, Pythagorean...
Harvard University
University of Harvard: This Is a Stickup!
Students are taught how to make a sundial. The relationship between angles and the sides of a right triangle are explored. Great lesson plan ideas with plenty of background information. The lesson plan is adapted for grade levels k-6...
Math Is Fun
Math Is Fun: Introduction to Trigonometry
Students are introduced to concepts taught in trigonometry. The tutorial consists of notes and examples.
Math Is Fun
Math Is Fun: Sine, Cosine, Tangent
Students learn about the sine, cosine, and tangent functions. The tutorial consists of notes, examples, and practice problems to check for comprehension.
Oswego City School District
Regents Exam Prep Center: Triangle Information
This Oswego City School District site from the Regents Exam Prep Center provides an explanation of the classifications of triangles both by sides and by angles. Pictures are also included.
Oswego City School District
Regents Exam Prep Center: Pythagorean Theorem
Who was Pythagoras and what is his theorem? Explore this concept and its relationship to the measurement of a right triangle in this test prep lesson plan. The lesson includes an interactive worksheet where students discover the answers...
Oswego City School District
Regents Exam Prep Center: Area of a Triangle and Parallelogram Using Trig
How can trigonometry be used to find the area of a triangle or parallelogram? Does the triangle need to be a right triangle, and how accurate can the results possibly be? The answers to these questions are found here along with several...
Khan Academy
Khan Academy: Reciprocal Trig Ratios
Understand the right triangle definition of sec, csc, and cot ratios. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Lawrence Hall of Science
The Math Page: Trigonometry: Solve Right Triangles
Here is a site that clearly and thoroughly explains how to solve right triangles for any missing side or angle given any two pieces other sides or angles. There are example problems solved, problems for the student to attempt, and...
Lawrence Hall of Science
The Math Page: Trigonometry: Trignometry of Right Triangles
Here is a site that clearly and thoroughly explains the trigonometry of a right triangle, including finding the values of all six trig functions given a single value. There are example problems solved, problems for the student to...
Lawrence Hall of Science
The Math Page: Trigonometry: The Isosceles Right Triangle
Here is a site that clearly and thoroughly explains the trigonometry of a 45-45-90 right triangle. There are example problems solved, problems for the student to attempt, and answers to the student problems. Point this site out to...
Lawrence Hall of Science
The Math Page: Trigonometry: The 30 60 90 Right Triangle
Here is a site that clearly and thoroughly explains the trigonometry of the 30-60-90 right triangle. There are example problems solved, problems for the student to attempt, and answers to the student problems. Point this site out to...
Purple Math
Purplemath: Basic Trigonometric Ratios: Examples
Demonstrates how to use trig ratios to do simple solving of triangles.
Physics Aviary
Physics Aviary: Triangle Exploration Lab
This lab is designed to have students look at some of the different relationships that exist in a right triangle. Students will be able to change the x-leg and y-leg of the triangle and then measure the angle and the hypotenuse of the...
CK-12 Foundation
Ck 12: 45 45 90 Triangles
[Free Registration/Login Required] Students use a baseball field to determine the distance between points and 45-45-90 triangles. Click learn more to watch a video and click challenge me to answer a practice question.
Khan Academy
Khan Academy: Distance Between Two Points
In this exercise, students practice using the distance formula, which is derived from the Pythagorean Theorem, to find the distance between two points on a coodinate grid. Students receive immediate feedback and have the opportunity to...
Khan Academy
Khan Academy: Special Right Triangles
Use your knowledge of 30-60-90 and 45-45-90 triangles to solve some problems. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Solve for an Angle in Right Triangles
Given two sides in a right triangle, find one of the acute angles using trigonometry. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Use Area of Squares to Visualize Pythagorean Theorem
Apply the Pythagorean theorem and its converse to solve these problems. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video, or receive hints.
Khan Academy
Khan Academy: Use Pythagorean Theorem to Find Isosceles Triangle Side Lengths
Find the missing side lengths of isosceles triangles by using the Pythagorean Theorem. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video, or receive hints.
BBC
Bbc: Pythagoras' Theorem
You can pick up some valuable pointers on how to apply the Pythagorean Theorem here. When you finish working your way through the pages you can take an on-line "Test Bite," and check your understanding.
Illustrative Mathematics
Illustrative Mathematics: G Co Classifying Triangles
The goal of this task is to help students synthesize their knowledge of triangles where only two of the vertices have been given. They will need to know that a triangle inscribed in a circle, with a diameter of the circle as one side, is...
Illustrative Mathematics
Illustrative Mathematics: G C, G Srt Setting Up Sprinklers
In this task, students must decide where to place sprinklers on a lawn so that the maximum area of the lawn will be watered. To solve it, they must find areas of sectors of circles and use trigonometric ratios to solve right triangles....