Texas Education Agency
Texas Gateway: Area of Triangles, Parallelograms, and Trapezoids
These activities provide an opportunity for students to explore the area formulas for triangles, trapezoids, and parallelograms.
Analyze Math
Analyze Math: Area of Triangles
The geometry resource explores the different formulas used to calculate the area of triangles. The applet investigates the angles and sides of a triangle.
Houghton Mifflin Harcourt
Holt, Rinehart and Winston: Homework Help: Perimeter and Area of Triangles and Trapezoids
Get independent practice working with finding the perimeter and area of triangles and trapezoids. Each incorrect response gets a text box explanation and another try. Correct responses are confirmed.
Math Is Fun
Math Is Fun: Area of Triangles Without Right Angles
Learn how to find the area of triangles without right angles. Find the formula to use depending on the information you know about the triangle: base and height, three sides, or two sides and an angle.
Better Lesson
Better Lesson: Area of Triangles
Sixth graders apply what they know about area of other polygons to develop a formula for finding the area of a triangle.
Texas Instruments
Texas Instruments: Area Formulas App
Students review the definition and area formula for the rectangle, square, parallelogram, triangle, trapezoid, and circle.
Texas Instruments
Texas Instruments: Getting Started With Area Formulas App
Calculate the Area of a Trapezoid This Concept Handheld Software Application reviews the definition and area formula for the rectangle, square, parallelogram, triangle, trapezoid, and circle.
CK-12 Foundation
Ck 12: Trigonometry: Derivation of the Triangle Area Formula
[Free Registration/Login may be required to access all resource tools.] Determine an alternate formula for a triangle's area.
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.
Free Math Help
Free Math Help: Area Formulas
The resource consists of area formulas and diagrams for a square, rectangle, circle, triangle, and trapezoid.
CK-12 Foundation
Ck 12: Geometry: Area and Perimeter of Triangles
[Free Registration/Login may be required to access all resource tools.] In this lesson students use formulas and given information to figure out the dimensions and the area of different triangles. Students examine guided notes, review...
Khan Academy
Khan Academy: Area of Triangles
Demonstrates the logic behind the formula for the area of a triangle. Includes several practice problems and their explanations.
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.
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.
National Council of Teachers of Mathematics
The Math Forum: Find the Area of the Shape!
Try to figure out the area of this challenging shape. In order to view the images, you will need to use JavaSketchpad.
Homeschool Math
Homeschool Math: Area of Triangles
This lesson presents the idea that the area of any triangle is exactly half of a certain parallelogram -- thus we get the familiar formula of multiplying the base and the altitude and taking half of that. The lesson contains varied...
Better Lesson
Better Lesson: Finding the Area of a Triangle
Sixth graders find the area of a triangle using square units and the area formula.
Cuemath
Cuemath: Right Angled Triangle
Explore and learn about the features and properties of a right triangle in this lesson. Includes examples and practice questions.
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.
Illustrative Mathematics
Illustrative Mathematics: 8.g Two Triangles' Area
In this task, 8th graders are given the dimensions of two isosceles triangles and are asked to compare their areas. They must draw them and use the Pythagorean Theorem and the triangle area formula to solve the problem. Aligns with 8.G.B.7.
Cool Math
Coolmath: Precalculus Basic Formulas to Know
This CoolMath resource provides an introduction to some Precalculus formulas.
Math Planet
Math Planet: Pre Algebra: Measure Areas
Demonstrates how to calculate the area of two-dimensional shapes using formulas. Covers parallelogram, triangle, trapezoid, and circle. Includes a video modeling how to find the area of a circle and a triangle. [0:59]
CK-12 Foundation
Ck 12: Geometry: Triangles and Quadrilaterals Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide reviews the formulas for area and perimeter of triangles and different kinds of quadrilaterals.
Oswego City School District
Regents Exam Prep Center: Area of a Triangle and Parallelogram Using Trig
How can trigonometry be used to find the area of a triangle or parallelogram? Does the triangle need to be a right triangle, and how accurate can the results possibly be? The answers to these questions are found here along with several...