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.
Discovery Education
Discovery Education: Web Math: Find Out Things About a Right Triangle
Gives basic info about a right triangle. Also students can substitute values for sides or angles in order to find missing values. The method for solving is then explained.
ClassFlow
Class Flow: Surface Area
[Free Registration/Login Required] In this lesson students learn how to find surface area of rectangular and triangular solids.
ClassFlow
Class Flow: Area of Polygons
[Free Registration/Login Required] This flipchart provides students with notes and practice with using formulas for finding the area of triangles and quadrilaterals.
Math Open Reference
Math Open Reference: Volume of a Triangular Prism
Use this interactive tool to find the volume of a triangular prism. Try different figures for the height and the dimensions of the triangular face to see how these affect the volume. An accompanying chart also presents five methods for...
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.
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...
CK-12 Foundation
Ck 12: Determination of Unknown Triangle Measures Given Area
[Free Registration/Login may be required to access all resource tools.] Looks at triangle problems where you are given the area and must use trigonometry to find unknown sides or angles.
Illustrative Mathematics
Illustrative Mathematics: 6.g Same Base and Height, Variation 2
This is the second version of a task asking students to find the areas of triangles that have the same base and height. This presentation is more abstract as students are not using physical models. They still determine the area of each...
Khan Academy
Khan Academy: Find Base and Height on a Triangle
Identify the height of a triangle when given the base. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Illustrative Mathematics
Illustrative Mathematics: G Srt Extensions, Bisections, Dissections in Rectangle
In this task, students must draw a diagram from a verbal description and use their understanding of similar triangles to find the area of a quadrilateral. Aligns with G-SRT.B.5.
Texas Instruments
Texas Instruments: Triangulation Problem
In this Computer Algebra System (CAS) activity, students use 'landscape' paper and fold the top left corner of the page so that it just touches the bottom of the page. They calculate the area of the triangle formed by the bottom left...
CK-12 Foundation
Ck 12: Interactive Geometry: 1.6 Area or Perimeter of Triangles/ Quadrilaterals
Explore finding and measuring perimeter of figures.
Illustrative Mathematics
Illustrative Mathematics: 8.g Circle Sandwich
Eighth graders are presented with a drawing of a large square inscribed by a circle which is itself inscribed by a second square. They are asked to find the area of the circle outside the smaller square and compare it to the area of the...
Calculator Soup
Calculator Soup: Isosceles Triangles Calculator
Use this calculator to find the sides, perimeter, area, semiperimeter, and altitude of an isosceles triangle.
CK-12 Foundation
Ck 12: Geometry: Unknown Dimensions of Triangles Grade 7
[Free Registration/Login may be required to access all resource tools.] Find unknown dimensions of triangles given area and one other dimension.
Other
Algebra Lab: Areas and Perimeters of Triangles and Special Quadrilaterals
Learn how to find the areas and perimeters of triangles and special quadrilaterals.
OER Commons
Oer Commons: Polygons
Seventh graders find the area of regular polygons, recalling what they already know about the area of geometric shapes and generalizing a formula for any regular polygon.
ClassFlow
Class Flow: Review of Area
[Free Registration/Login Required] This flipchart is a review of calculating the area of squares, rectangles, and triangles for fifth graders. It also includes problems that work backwards from the area to find missing dimensions. It...
Maths Challenge
Maths challenge.net: Maximum Square
A challenging proof like geometry of finding the square inscribed in a triangle.
Texas Instruments
Texas Instruments: Heron's Formula
This activity allows students to find the area of a triangle using Heron's formula.
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...
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.
Calculator Soup
Calculator Soup: Right Triangles Calculator
Use this calculator to find the unknown angles in a right triangle using the Pythagorean Theorem. Once you know the sides you can calculate the perimeter, semiperimeter, area, and the altitudes.