Wolfram Research
Wolfram Math World: Midpoint
This MathWorld site offers a lesson on finding the midpoint of a line segment using a compass and finding the midpoint of the sides of a triangle. This site also has an interesting way of drawing two triangle with equal area by finding...
Texas Instruments
Texas Instruments: Numb3 Rs: Location! Location! Location!
Based off of the hit television show NUMB3RS, this lesson introduces students to Voronoi diagrams, which split a plane into regions corresponding to distances to given points. The lesson is framed in the context of splitting a city into...
CK-12 Foundation
Ck 12: Trigonometry: Heron's Formula
[Free Registration/Login may be required to access all resource tools.] Find the area of a triangle when all three sides are known.
Math Open Reference
Math Open Reference: Volume of a Triangular Prism
A complete reference guide to finding the volume of a triangle prism. It provides definitions, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
Illustrative Mathematics
Illustrative Mathematics: G C, G Srt Neglecting the Curvature of the Earth
Jerry and Ashley are trying to find out if it is possible to see the lowest point in the USA from the highest point in the USA. It turns out that the highest point in the United States, the peak of Mount Whitney, is only 85 miles from...
Other
The mathlab.com: Sophia's Tree of Mysteries
There are 10 questions hidden in the tree. Click around to find them. As you find each answer, use the decoder grid below to find its matching letter to determine the required password to enter the restricted area.
OER Commons
Oer Commons: Exploring Polygons
For this lesson, students explore different polygons by drawing them, measuring angles, and manipulating interactive sketches to find the angle sum for any polygon. Students also explore the angle measures in regular polygons. Included...
Purple Math
Purplemath: Determinant Word Problems
Matrix determinants can be used to solve many algebra and geometry word problems. Among them: finding the area of a triangle, finding the area of a parallelogram, and finding the equation of a line between two points. These three...
ClassFlow
Class Flow: The Law of Cosines
[Free Registration/Login Required] This flipchart defines and uses the law of cosines to find the missing sides and angles of oblique triangles.
Texas Instruments
Texas Instruments: Heron's Formula
This activity allows students to find the area of a triangle using Heron's formula.