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Interactive
CK-12 Foundation

Alternate Formula for the Area of a Triangle: Alternate Area of a Triangle

For Students 10th - 12th
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.
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Activity
Noyce Foundation

Lyle's Triangles

For Students K - 12th Standards
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....
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Lesson Plan
Alabama Learning Exchange

Polygons-Changing Area Versus Changing Perimeter

For Teachers 5th - 8th Standards
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...
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Instructional Video6:29
Corbett Maths

Pythagoras Rectangles and Isosceles Triangles

For Students 7th - 12th Standards
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...
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Instructional Video14:56
Corbett Maths

Area under a Graph

For Students 8th - 12th Standards
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...
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Worksheet
Curated OER

Perimeter and Area

For Students 3rd - 8th
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.
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Interactive
Curated OER

Coordinate Planes - Area of Triangle

For Students 9th - 12th
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...
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Worksheet
Curated OER

Perimeter and Area of Triangles (B)

For Students 4th - 5th
In this geometry activity, students calculate the perimeter and area for each of 4 triangles using the given measurements. They work with measurements that are labeled in centimeters.
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Worksheet
Curated OER

Area Of Triangles

For Students 4th - 8th
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.
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Worksheet
Curated OER

Area of Right-Angled Triangles

For Teachers 3rd - 5th Standards
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...
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Lesson Plan
Curated OER

Finding the Area of an Equilateral Triangle

For Teachers 9th - 11th Standards
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...
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Lesson Plan
Illustrative Mathematics

Finding Areas of Polygons, Variation 1

For Teachers 5th - 9th Standards
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...
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Worksheet
Curated OER

Similar Triangles and Trapezoids, and Circles

For Students 9th - 12th
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.
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Lesson Plan
Texas Instruments

Identifying a Triangle by its Sides and Angles

For Teachers 9th - 12th Standards
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,...
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PPT
Curated OER

Area and Perimeter

For Teachers 4th - 5th
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...
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Lesson Plan
Curated OER

Ratios for Area and Volume

For Teachers 5th - 8th
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.
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Lesson Plan
Curated OER

Area of Tangram Pieces

For Teachers 3rd - 4th
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...
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Lesson Plan
Hotchalk

Triangle Sum Theorem

For Teachers 8th - 10th Standards
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...
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Lesson Plan
Curated OER

Finding the Area of Shapes

For Teachers 3rd - 5th
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...
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Lesson Plan
Curated OER

The Pythagorean Theorem and Classifying Triangles

For Teachers 9th - 12th Standards
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).
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Interactive
Scholastic

Study Jams! Area of Irregular Figures

For Students 5th - 8th Standards
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,...
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Worksheet
Curated OER

Area of Triangle

For Students 5th - 6th
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.
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Lesson Plan
EngageNY

Using Trigonometry to Determine Area

For Students 9th - 10th Standards
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...
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Lesson Plan
Alabama Learning Exchange

Triangle Area: No Height? Use the Sine

For Students 9th - 12th Standards
No height? No problem! Learners use their knowledge and a little help from GeoGebra to develop the Law of Sines formula. The Law of Sines helps to determine the height of triangles to calculate the area.

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