Shodor Education Foundation
Triangle Area
While the lesson focuses on right triangles, this activity offers a great way to practice the area of all triangles through an interactive webpage. The activity begins with the class taking a square paper and cutting in in half; can they...
EngageNY
Perimeter and Area of Triangles in the Cartesian Plane
Pupils figure out how to be resourceful when tasked with finding the area of a triangle knowing nothing but its endpoints. Beginning by exploring and decomposing a triangle, learners find the perimeter and area of a triangle. They...
Education Development Center
Finding Triangle Vertices
Where in the world (or at least in the coordinate plane) is the third vertex? Given two coordinate points for the vertices of a triangle, individuals find the location of the third vertex. They read an account of fictional...
5280 Math
Triangle Area Patterns
Combine algebraic and geometric strategies to find solutions. The task asks learners to find the coordinates of a third vertex of a triangle to create a triangle with a specific area. The project is a set of seven problems that...
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
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.
Virginia Department of Education
Area and Perimeter
Develop a strategy for finding the area and perimeter of irregular figures. Building on an understanding of finding area and perimeter of rectangles and triangles, learners apply the same concepts to composite figures. After...
Curated OER
Finding Area of Similar Figures
Students explore the concept of finding area of similar figures. In this finding area of similar figures lesson, students use pattern blocks to construct similar figures. Students trace their construction and find the area. Students...
EngageNY
Perimeter and Area of Polygonal Regions Defined by Systems of Inequalities
When algebra and geometry get together, good things happen! Given a system of inequalities that create a quadrilateral, learners graph and find vertices. They then use the vertices and Green's Theorem to find the area and perimeter of...
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
The Pythagorean Theorem and Classifying Triangles
Through the examination of the relationship between the lengths of the sides of a triangles learners will learn the classification of triangles (acute, right, or obtuse).
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
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...
Alabama Learning Exchange
Triangle Area: No Height? Use the Sine
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.
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...
EngageNY
Real-World Area Problems
Not all structures take the shape of a polygon. The 21st lesson in a series of 29 shows young mathematicians they can create polygons out of composite shapes. Once they deconstruct the structures, they find the area of the composite figure.
Radford University
Finding the Largest Possible Area
If you want a bigger garden, here's a task for you. Given the perimeter of a triangular garden, scholars determine the largest possible area. They then generalize their findings and extend the idea to other polygons.
Curated OER
Special Right Triangles
Using the Pythagorean Theorem to solve for missing angles, learners evaluate right triangles and their properties.
Curated OER
What's My Area?
Young scholars use tiles to find area. In this finding area lesson, students explore how to use square tiles to make shapes, then look at how they can be used to measure area. Young scholars then explore how an area can be covered with...
Curated OER
Areas of Polygons
Young mathematicians calculate the area of polygons in this algebra lesson. They find the determinant as they calculate the areas for triangles and quadrilaterals. They also use scalar multiplication to find the determinant.
Curated OER
Unit Squares and Triangles
This is an interesting geometry problem. Given the figure, find the area of a triangle that is created by the intersecting lines. The solution requires one to use what he/she knows about coordinate geometry, as well as triangle...
Curated OER
Area Measures and Right Triangles
Your class will investigate the relationship among different triangles. This geometry lesson, demonstrates how to make a connection between triangles and the Pythagorean Theorem. They identify the missing side or angle of a triangle.
Curated OER
Exploring the Circumcenter of a Triangle
Students construct the circumcenter of a triangle. For this constructing the circumcenter of a triangle lesson, students construct a triangle using Cabri Jr. Students draw perpendicular bisectors of the sides of the triangle. Students...
Curated OER
Measuring Angles in a Triangle
High schoolers investigate the sum of the measures of the angles of a triangle. They draw a triangle and measure the interior angles. Using Cabri Jr., learners find the sum of the measures of the interior angles. The activity provides an...