Other
Trigonometry: A Quick Review
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...
Khan Academy
Khan Academy: Challenge Problems: Circumscribing Shapes
Solve two challenging problems that apply properties of tangents to find the perimeter of a circumscribing shape.
CK-12 Foundation
Ck 12: Algebra Ii: 4.8 Pythagorean Identities
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.
Mangahigh
Mangahigh: Pyramid Panic: Basic Shapes to Advanced Geometry
Guide a mummy safely through the burial chambers of a pyramid as you solve length and area problems in basic to advanced geometry. There are four game zones that deal with circles and triangles, quadrilaterals, the Pythagorean Theorem,...
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Tangencias
In Spanish. This interactive unit introduces various geometric concepts which are intended to be tools for solving problems of tangencies between straight lines, circles and points.
Curated OER
Trig Function Point Definitions
A java applet that relates the unit circle to the graphs of the six trigonometric functions, complete with the values of the functions.
Northeast Parallel Architectures Center, Syracuse University
Npac Reu Program: Trigonometric Functions
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.
Lawrence Hall of Science
The Math Page: Trigonometry
Concepts in Trigonometry are explained and illustrated here by a member of the math department at Borough of Manhattan Community College.
Curated OER
University of St Andrews: Apollonius
This is a biography of Apollonius who showed how to draw a circle tangent to 3 given circles.
Other
Ctte: Geometer's Sketch Pad Activities
This site offers numerous activities for middle school and high school students to explore using Geometer's Sketch Pad.