Purple Math
Purplemath: Sectors, Areas, and Arcs
Explains formulas for areas of sectors of circles and lengths of arcs. Demonstrates how to use the formulas in each of degrees and radians.
CK-12 Foundation
Ck 12: Trigonometry: Sides of an Oblique Triangle
[Free Registration/Login may be required to access all resource tools.] This lesson covers using the Law of Cosines to find the third side of a triangle.
CK-12 Foundation
Ck 12: Determination of Unknown Angles Using Law of Cosines
[Free Registration/Login may be required to access all resource tools.] This lesson covers using the Law of Cosines to find an angle in a triangle.
Math Planet
Math Planet: Algebra 2: Angles
Features a definition, examples, and a video lesson all related to angles. [0:35]
Math Open Reference
Math Open Reference: Angle
Learn about angles with this helpful reference tool. Provides a detailed definition, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
Math Open Reference
Math Open Reference: Arc Length
Learn about arc length with this handy reference guide. Provides a detailed definition examples, and an interactive activity that enhances further explanation. Includes links to related topics.
CK-12 Foundation
Ck 12: Trigonometry: Pythagorean Theorem for Solving Right Triangles
[Free Registration/Login may be required to access all resource tools.] This lesson applies the trigonometric ratios and their inverses to real-life situations.
Math Words
Math Words: Sector of a Circle
This site offers a picture and short discussion of a sector of a circle. The site contains a link to the area of a sector of a circle in both degrees and radians. There are links to related words.
Math2
Math2.org: Trigonometry Functions
A complete look at trig functions. From an "overview," page giving general definitions and important vocab words, to a listing of the 12 trig functions, to an explanation of the three modes used in trigonometry, to the procedures of how...
Other
Gobierno De Navarra: Trigonometria
Use these interactive activities as a supplementary material to visualize some basic concept of Trigonometry.