Explains the basic concept of congruent triangles with step-by-step instructions and methods for solving specific problems on your own relating to this topic.

Some friends are at the beach looking out onto the ocean on a clear day and they wonder how far away the horizon is. A second problem asks how far the horizon would be from the top of a mountain. Students must also answer a question...

Three circles are mutually tangent. Students are asked to find the total area of the circles plus the area inside where they meet. Students will need to know how to calculate the area of a circle, a sector of a circle, and an equilateral...

In this activity, students will investigate properties of angles and arcs formed when chords, secants, and tangents intersect and intercept arcs in a circle. They discover several important theorems concerning circles and arc sizes. They...

[Free Registration/Login Required] Students can adjust the size of the circle to explore the tangent lines. Click learn more to watch a video and click challenge me to answer a practice question.

The Clark University site shows and explains the graphs of the six trigonometric functions. It explains how to find an arbitrary angle measurement using trig. Also, it explains that sine and cosine functions are complementary.

Explains the basic concept of chords with step-by-step instructions and methods for solving specific problems on your own relating to this topic.

In the July 2013 issue of United Airlines' Hemisphere Magazine, a pilot responded to a question about how far in the distance he could see at different altitudes. The solution involved right triangles, lines of tangency to a circle, and...

[Free Registration/Login Required] Students identify segments and lines related to circles and the properties of a tangent to a circle.

Using known facts about the unit circle and isosceles triangles together with the Pythagorean Theorem, students can derive the sine and cosine of special angles. Aligns with HSF-TF.A.3.

Using known facts about the unit circle and isosceles triangles together with the Pythagorean Theorem, young scholars can derive the sine and cosine of special angles. Aligns with HSF-TF.A.3.

Find the sine and cosine of special angles, which are angles whose trig values we can determine without the use of a calculator. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or...

This Northeast Parallel Architectures Center of Syracuse University site offers a quick overview of the six trigonometric functions from the standpoint of the unit circle.

Concepts in Trigonometry are explained and illustrated here by a member of the math department at Borough of Manhattan Community College.

Students are introduced to concepts taught in trigonometry. The tutorial consists of notes and examples.

You know that you can take side lengths and find trig ratios, and you know you can find trig ratios (in your calculator) for angles. What is missing is a way to go from the ratios back to the original angles. And that is what "inverse...

In Spanish. Interactive activities online on various geometric and trigonometric concepts such as area, perimeter, secants, tangents, etc. A terrific resource for students. Site is organized acoording to shape. (triangle, quadrilaterals,...

This online trigonometry calculator will calculate the sine, cosine, tangent, cotangent, secant and cosecant of angle values entered in degrees or radians. The trigonometric functions are also known as the circular functions.

This online trigonometry calculator will calculate the sine, cosine, tangent, cotangent, secant and cosecant of values. The trigonometric functions are also known as the circular functions.

This site is a personal site from David Eisenberg and it contains brief but great review information for trigonometry. This particular site focuses on sine and cosine inlcuding a small circle graph. Clicking on the index link provides...

Formulas and illustrations show the different kinds of angles created by intersecting tangents, secants, radii, and in combination.

This section explores the Pythagorean Identity and how it applies to right triangles set inside unit circles, in terms of sine, cosine, and tangent functions.

This site from MathWorld explains the hyperbolic function. The information is not too in-depth, but factual and quite a few links are provided for additional information on related subjects.

In Spanish. This interactive unit could be used as a visual review of circles, circumference and tangents.