CK-12 Foundation
Alternate Formula for the Area of a Triangle: Alternate Area of a Triangle
It's always nice to have a plan B. Pupils investigate an alternate formula for the area of a triangle that uses sine. A set of challenge questions shows how the new formula relates to the well-known formula of (1/2)bh.
Noyce Foundation
Lyle's Triangles
Try five problems on triangles. Levels A and B focus on shapes that can be created from right triangles. Level C touches upon the relationship between the area of a six-pointed star and the area of each triangle of which it is composed....
Alabama Learning Exchange
Polygons-Changing Area Versus Changing Perimeter
Investigate the area and perimeter of polygons in this geometry lesson. Young geometers use grid paper to draw a quadrilateral and calculate its area and perimeter. They also read The Greedy Triangle to identify the changing shape of...
Corbett Maths
Pythagoras Rectangles and Isosceles Triangles
When does the Pythagorean Theorem come in handy? An intriguing video uses the Pythagorean Theorem to solve problems other than simply finding the length of a side of a right triangle. Pupils find the diagonal of a rectangle and the...
Corbett Maths
Area under a Graph
What? The calculation of area is a linear distance? A short video shows how to use the areas of simple polygons to estimate the area under a graph. Pupils divide the area under a curve into figures to easier calculate the area. Given...
Curated OER
Perimeter and Area
Use this perimeter and area worksheet to have learners find the perimeter and area of shapes with right angles. They complete a total of nine problems.
Curated OER
Coordinate Planes - Area of Triangle
In this online math worksheet, students find the area of a variety of triangles given the measurements of their vertices. This excellent resource allows the students to check their answers, and to get "hints" should they run into...
Curated OER
Perimeter and Area of Triangles (B)
In this geometry worksheet, students calculate the perimeter and area for each of 4 triangles using the given measurements. They work with measurements that are labeled in centimeters.
Curated OER
Area Of Triangles
In this math worksheet, students complete 19 problems where they find the area of triangles by utilizing a variety of shapes and numbers. This worksheet would be an excellent homework assignment.
Curated OER
Area of Right-Angled Triangles
There's a trick to solving the area of a triangle, and it involves a skill your geometers have already mastered. Help them discover the connection between finding a rectangle's area and finding a right triangle's area as they solve for...
Curated OER
Finding the Area of an Equilateral Triangle
The problem seems simple: find the area of the equilateral triangle whose sides are each length 1. In fact, this same problem is solved in 8th grade, addressing a different Common Core standard, using the formula for area of a triangle...
Illustrative Mathematics
Finding Areas of Polygons, Variation 1
An exercise in finding the area of polygons by decomposing into triangles and composing into rectangles is the focus of this resource. Make several copies of the worksheet for each participant. Ask learners to use colored pencils to...
Curated OER
Similar Triangles and Trapezoids, and Circles
High schoolers answer two problems involving area of shaded regions. Students then answers six questions involving perimeter, area, and circumferences. The remaining two questions involve ratios of similar figures.
Texas Instruments
Identifying a Triangle by its Sides and Angles
Identify triangles by their angle measures and side lengths by looking at and measuring angle measures and side lengths. Use Cabri Jr. to construct various triangles, then manipulate the construction to create the 6 types of triangles,...
Curated OER
Area and Perimeter
Another good presentation by Christine Berg is here for you. In it, learners are coached on definitions of area and perimeter and are shown how to perform calculations for both. They also see how to calculate the area of a triangle by...
Curated OER
Ratios for Area and Volume
In this ratios for area and volume worksheet, students solve problems where they find the ratios for problems of shapes dealing with area and volume. Students complete 4 problems.
Curated OER
Area of Tangram Pieces
Mathematicians calculate the area of a tangram piece without using formulas. They use a geometry journal to record activities during this lesson. They make a set of tangrams and use them to compute area. They use what they discover to...
Hotchalk
Triangle Sum Theorem
Your visual geometry learners will appreciate triangle drawings as they model the triangle sum theorem and algebraically solve to find the missing interior angle in a triangle. Practice problems increase in complexity and vary in their...
Curated OER
Finding the Area of Shapes
In this area of shapes unit, upper graders participate in hands-on problem solving activities to find the formulas for the area of a parallelogram, a triangle, and a trapezoid. They manipulate the geoboard to explore relationships among...
Curated OER
The Pythagorean Theorem and Classifying Triangles
Through the examination of the relationship between the lengths of the sides of a triangles high schoolers will learn the classification of triangles (acute, right, or obtuse).
Scholastic
Study Jams! Area of Irregular Figures
Painting an irregular figure can be tricky if we don't know the exact area. This interactive presentation reveals that irregular figures can be broken into smaller, simple figures that use the area formulas. Go through two examples,...
Curated OER
Area of Triangle
In this area of a triangle learning exercise, students solve 3 problems where they calculate the area of a triangle when they are given the length of the base and the height and the formula.
EngageNY
Using Trigonometry to Determine Area
What do you do when you don't think you have enough information? You look for another way to do the problem! Pupils combine what they know about finding the area of a triangle and trigonometry to determine triangle area when they don't...
Concord Consortium
Strings and Areas
You'd be surprised what you can do with a string! The constraint is the length of string, and the task is to maximize area. Given a series of composite shapes, learners must create a formula for the maximum area for a specified...