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 and angle...
Curated OER
Scale Factor Area Perimeter
Mathematicians compare triangles at different scales. In this geometry lesson, students calculate the area and perimeter of triangles. They use the Ti to make observation of the change that takes place as the triangles are dilated.
Curated OER
Nested Similar Triangles
Nested triangles have been created so that they share a common vertex and vertex angle. Learners drag the endpoints of the side that is opposite the common angle to discover the conditions that make the nested triangles similar. When...
Curated OER
Triangle Midsegment
Learn how to calculate the length and midsegments of triangles. Students differentiate between similar and congruent triangles. They create a spreadsheet with their findings.
Curated OER
Similar Figures
Your class will use a TI calculator to drag vertices of rectangles and triangles to observe what happens to ratios of pairs of sides within each figure. They will apply the definition of similarity to identify similar shapes. The lesson...
Curated OER
Angles and Similarity
High schoolers identify triangles as similar or congruent. In this geometry lesson, students drag triangles around on the navigator to see the effect of different angles on the shape of the triangle. They discuss angle similarity and...
Curated OER
Congruent Triangles
Students identify properties of triangles. For this geometry lesson, students differentiate between similar and congruent triangles. They use the umber of sides to help define the angle of the polygon.
Curated OER
Corresponding Parts of Similar Triangles
Here is a lesson that has learners take a look at corresponding parts of similar triangles, ratios of similarity, reductions and enlargements. They'll manipulate the scale factor (r) to observe the changes in similar triangles and then...
Curated OER
Ratios of Similar Figures
Students identify the ratios of different triangles. In this geometry lesson, students identify the similarity and differences of triangles. They use the navigator to move the sides of the triangle around.
Curated OER
Altitude to the Hypotenuse
Can your class solve right triangles and identify the properties common to right triangles? They will investigate and state the relationship between the altitude to the hypotenuse and the two segments of the hypotenuse formed by the...
Curated OER
Trigonometry Ratios
Students identify the different angles and sides of a triangle. In this geometry instructional activity, students identify the six trigonometric ratios. They graph the graph of each trig function and analyze it.
Key Curriculum Press
Triangle Inequalities
Properties about triangles are explored in this lesson. Geometers make conjectures about the length of a triangle's sides, the length of the angles in relation to the length of the sides, and the measure of the exterior angles of a...
Curated OER
Properties of Parallelograms
High schoolers discover properties of parallelograms as they construct a parallelogram using Cabri Jr. They will measure angles and side lengths of their construction and determine the relationship between the diagonals of a...
Curated OER
Similar Triangles and Proportions
Pupils investigate similar triangles and proportions as they make conjectures about the length of sides of similar triangles. For this lesson, have your class construct similar triangles using Cabri Jr so that they share a common vertex.
Texas Instruments
What's the Trig?
Learners determine the trigonometric relationships within a triangle as they construct a right triangle on the Ti-89. They find the sine, cosine, and tangent of various angles of their triangle construction.
Curated OER
Investigating Area Relationships
Learners investigate the area of various figures. They construct triangles and quadrilaterals using Cabri Jr. and discuss the relationships between different angles, side lengths, and figures.
Curated OER
Investigating Segments in a Triangle
Pupils investigate segments in a triangle by constructing a triangle using Cabri Jr. They construct segments within the triangle that lie on the midpoints of the triangle's sides. Learners then compare the slope of base of the triangle...
Curated OER
Investigating Lengths of Segments in a Triangle
Pupils explore the midsegment of a triangle in the geometry lesson. They draw and measure the segment joining the midpoints of the two sides of a triangle and compare its length to the length of the third side of the triangle. The...
Curated OER
Sail Problem
High schoolers explore the proportional relationships involved in multiple parallel lines being cut by a transverse line. They complete a sail design problem, that involves finding the lengths of pieces of fabric along the edge of a sail...