Mathed Up!
Sine and Cosine Rules and Area of Triangles
Learners discover how to find missing sides and angles using trigonometry. Scholars first watch a video covering the Law of Sines and Cosines, as well as the area formula for a triangle. To test their knowledge, they complete a worksheet...
Curated OER
Area of a Triangle: English Learner 16.4
In this ELL triangle worksheet, students review the definition of a triangle and then draw dotted lines to show the height of each figure. If one side is the height, students circle that side.
Illustrative Mathematics
Base and Height
It is easy to find the area of a triangle where the base and the height are given. But in this resource, it is up to your geometers to identify the base and height of the triangle. In fact, your pupils will learn that there are three...
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...
EngageNY
Perimeter and Area of Polygonal Regions in the Cartesian Plane
How many sides does that polygon have? Building directly from lesson number eight in this series, learners now find the area and perimeter of any polygon on the coordinate plane. They decompose the polygons into triangles and use Green's...
Curated OER
Who Wants to Be a Champion: Perimeter, Area, Symmetry
Have your learners practice finding the perimeter and area of geometric shapes using this resource. While just a simple review, this could be a wonderful way to solidify the concepts in their minds.
Curated OER
Perimeter and Area 5
In this calculating area worksheet, middle schoolers use their problem solving skills and the information provided to find the area of 6 triangles.
CK-12 Foundation
Area Between Curves: Income and Expenses
Use the area of polygons to calculate the area between curves. Pupils calculate areas under income and expense curves by filling the space with squares and right triangles. Using that information, they determine the profit related to the...
Curated OER
Hands On: Area of Triangles
In this area of triangles practice activity, students sharpen their problem solving skills as they solve 6 story problems.
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
Finding the Area of Polygons
Third graders are exposed to finding the area of polygons by decomposing figures and recomposing them into rectangles. This strategy allows children to expand on their prior knowledge of constructing shapes by rearranging parts into...
Curated OER
Investigation Area of Geometric Shapes
Fourth graders use triangle paper to design patterns using geometric figures and find the areas of those figures by counting units. Students are assessed by determining which figure has the greatest area and explaining their reasoning.
Curated OER
Area of Triangle Worksheet
In this area worksheet, students find the area of a triangle given the height and the base. They also find the height or base given the area of the triangle. 
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...
Flipped Math
Unit 9 Review: Area of Polygons
It's time to show what you know! Individuals first review finding the area of polygons using the formulas from parallelograms to regular polygons. They then brush up on finding the area and circumference of circles, as well as reviewing...
Mathed Up!
Surface Area
Surface area is the sum of the parts. Given the measurements of different prisms, pupils determine their surface areas. Individuals find the area of each surface and figure out the surface area by finding the sum. The video, part of a...
Curated OER
Area of Triangle
In this area of a triangle worksheet, 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.
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
Triangle Series
Your algebra learners emphasize the"geometric" in geometric series as they use a common ratio between algebraic terms and find that it corresponds to a repeated similarity transformation. 
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...
Mathematics Assessment Project
Solving Problems with Circles and Triangles
After completing a task involving examining the ratio of areas of triangles and circles in a given figure, scholars examine sample responses to identify other strategies they could use to solve the problem.
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...
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,...
Math Mammoth
Finding the Area of Rectangles, Parallelograms, and Triangles
In this area of polygons activity, 9th graders solve two area of rectangles, one area of parallelogram, and ten area of triangles problems.  The formulas for finding the area of these figures are provided.