CK-12 Foundation
Ck 12: Trigonometry: Alternate Formula for the Area of a Triangle
[Free Registration/Login may be required to access all resource tools.] An alternate formula for the area of a triangle.
Wolfram Research
Wolfram Math World: Area
Definitions and formulas for the computation of surface areas of triangles, rectangles, and any regular polygon. Helpful links to related pages.
National Council of Teachers of Mathematics
Nctm: Illuminations: Igd: Area of a Triangle
Use this interactive tool to learn how to find the area of a triangle. Click on "Instructions" for details on how to use this tool. Click on "Explore" for more ideas. [Requires Java.]
CK-12 Foundation
Ck 12: Trigonometry: Introduction to the Triangle Area Formula
[Free Registration/Login may be required to access all resource tools.] This lesson covers how to find the area of a triangle using sine.
Cool Math
Coolmath: Precalculus Basic Formulas to Know
This CoolMath resource provides an introduction to some Precalculus formulas.
Math Open Reference
Math Open Reference: Heron's Formula
Learn about corresponding angles with this resource which offers detailed explanations, examples, and interactives. Subjests covered include the area of a triangle. Links to related topics.
Math Open Reference
Math Open Reference: 45 45 90 Triangle
Explore the triangle inequality theorem with this helpful reference tool. Provides a detailed definition and an interactive activity that enhances further explanation. Includes links to related topics.
George Mason University
Area Formula Lab
In this set of worksheet activities, students will be guided to discover formulas for area of polygonal shapes and circles.
Sophia Learning
Sophia: Understanding the Area of a Triangle
This lesson will explore ways to determine the area of a triangle.
Free Math Help
Free Math Help: Area Formulas
The resource consists of area formulas and diagrams for a square, rectangle, circle, triangle, and trapezoid.
Mr. Martini's Classroom
Mr. Martini's Classroom: Area of Triangles, Trapezoids & Parallelograms
Students solve for the area of rectangles, squares, triangles, trapezoids, and parallelograms.
University of Cambridge
University of Cambridge: Nrich: Disappearing Square
This one page website explains how to find the area of a triangle with an interactive graphic. It then offers a challenge. The solution is available right at the website.
University of Cambridge
University of Cambridge: Nrich: Adding Triangles
Sharpen your logic and geometry skills by finding the area of a triangle. Solution available.
Varsity Tutors
Varsity Tutors: Hotmath: Review: Area
Find a quick, concise explanation of area and the formulas for different shapes. An example is given to help you understand how find the area of a shape. The area formulas are listed for different types of shapes.
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...
Calculator Soup
Calculator Soup: Isosceles Triangles Calculator
Use this calculator to find the sides, perimeter, area, semiperimeter, and altitude of an isosceles triangle.
Mocomi & Anibrain Digital Technologies
Mocomi: What Is Heron's Formula?
Define's Heron's Formula and provides examples for how to use the formula to calculate the area of a triangle.