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Lesson Plan
EngageNY

Similarity

For Students 9th - 10th Standards
Learn similarity through a transformations lens! Individuals examine the effects of transformations and analyze the properties of similarity, and conclude that any image that can be created through transformations is similar. The...
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Lesson Plan
1
1
Illustrative Mathematics

Right Triangles Inscribed in Circles I

For Teachers 9th - 10th Standards
One of the basic properties of inscribed angles gets a triangle proof treatment in a short but detailed exercise. Leading directions take the learner through identifying characteristics of a circle and how they relate to angles and...
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Lesson Plan
Curated OER

Triangle Congruence with Coordinate

For Teachers 7th - 9th Standards
Two triangles are displayed on a coordinate plane. Youngsters apply a reflection and a translation to demonstrate their congruence. This exercise makes a terrific tool for teaching these concepts, or a way to assess learning.
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Worksheet
Curated OER

Glencoe - Proportions and Similar Triangles

For Students 9th - 12th
In this proportions and similar triangles learning exercise, students solve 14 multiple choice problems. Students find unknown sides of similar triangles using proportions. Students multiply means and extremes to solve proportions.
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Activity
Education Development Center

Similar Triangles

For Students 8th - 10th Standards
Model geometric concepts through a hands-on approach. Learners apply similar triangle relationships to solve for an unknown side length. Before they find the solution, they describe the transformation to help identify corresponding sides.
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Interactive
CK-12 Foundation

Special Triangle Ratios: Special Right Triangle Ratios

For Students 9th - 12th Standards
Go from one side length to any other side length with special right triangles. Individuals use the interactive to investigate the ratio of sides in 45-45 and 30-60 right triangles. Scholars make generalizations about the types of special...
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Interactive
CK-12 Foundation

Determination of Unknown Triangle Measures Given Area: Jib Sheets

For Students 10th - 12th Standards
Solving triangles is a breeze. Young boat enthusiasts solve problems involving triangles in the context of sails on a boat. They must apply different strategies, including the Law of Cosines and area formulas.
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Lesson Plan
EngageNY

Congruence Criteria for Triangles—SAS

For Students 9th - 10th Standards
Looking for a different approach to triangle congruence criteria? Employ transformations to determine congruent triangles. Learners list the transformations required to map one triangle to the next. They learn to identify congruence if...
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Lesson Plan
Mathematics Assessment Project

Solving Problems with Circles and Triangles

For Teachers 9th - 12th Standards
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.
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Interactive
CK-12 Foundation

Right Triangles, Bearings, and Other Applications: Sailing Race

For Students 9th - 12th Standards
Help your class get their bearings when it comes to right triangles. Pupils determine distances traveled or components given the bearing of a sailboat using an interactive. The scholars develop a sense of finding the bearings of a given...
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Interactive
CK-12 Foundation

Distance Formula: Right Triangles

For Students 8th - 10th Standards
Go the distance with a far out resource. Individuals use an interactive to create right triangles on a coordinate plane to help find distance between two points. Challenge questions aid them in developing the distance formula.
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Interactive
CK-12 Foundation

Angle-Angle-Side Triangles: Garden Gate

For Students 10th - 12th Standards
Good fences make good gardens. Individuals use an interactive to see how angles and sides relate in a triangular-shaped garden fence. They apply the Law of Sines to find the length of the garden gate (third side of triangle) given two...
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Interactive
CK-12 Foundation

Possible Triangles with Side-Side-Angle

For Students 10th - 12th
It's not often that math allows for multiple answers. Young mathematicians identify possible numbers of triangles when given two sides and a non-included angle. An interactive helps with this investigation.
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Unit Plan
Massachusetts Department of Education

Similarity through Transformations

For Teachers 9th - 12th Standards
Create the ultimate miniature golf course. The 93-page model curriculum unit from the Massachusetts Department of Elementary and Secondary Education contains nine lessons on understanding similarity in terms of both Euclidean geometry...
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Interactive
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GeoGebra

Triangle Dilations

For Students 9th - 12th Standards
Stretch the class' knowledge of dilations. With the aid of the rubber band stretcher tool, learners perform dilations. They dilate the triangle by a whole number scale and a fractional scale from two centers of dilation.
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Worksheet
Curated OER

Parts of Similar Triangles

For Students 10th
In this parts of similar triangles learning exercise, 10th graders solve 6 different problems related to determining the value of various parts of similar triangles. First, they find the value of x in the 2 figures shown. Then, students...
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Worksheet
Curated OER

Similar Figures

For Students 7th - 10th
In this similar figure worksheet, students find the length of a missing side of given triangles and quadrilaterals.  This six-page worksheet contains 24 problems.  Answers are provided on the last page.
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Assessment
Inside Mathematics

Rhombuses

For Teachers 9th - 12th Standards
Just what does it take to show two rhombuses are similar? The assessment task asks pupils to develop an argument to show that given quadrilaterals are rhombuses. Class members also use their knowledge of similar triangles to show two...
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Interactive
CK-12 Foundation

Trigonometric Functions and Angles of Rotation: The Triangle in the Circle

For Students 10th - 12th Standards
Go around the unit circle and create triangles. Pupils move a point around the unit circles to visualize the triangle associated with the angle in standard position. The three main trigonometric functions are defined in terms of the legs...
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Lesson Plan
Curated OER

When Does SSA Work to Determine Triangle Congruence?

For Teachers 9th - 10th Standards
Your learners will make good use of the Socratic method in a collaborative task that begins with an assumed solution and ends with deeper understanding of the idea of determining two triangles congruent.
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Performance
Radford University

Triangles in Parallelograms

For Teachers 9th - 12th Standards
What's the point of looking at triangles when trying to draw parallelograms? Given three non-collinear points, pupils determine and justify all possible points that would create a parallelogram. They then analyze the four triangles that...
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Lesson Plan
Curated OER

Triangles

For Teachers 6th - 10th
Students identify triangles in the real world and construct their own triangle using drinking straws. They explore abstract triangles and find additional geometric shapes such as trapezoids. Students discuss similar shapes and examine...
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Lesson Plan
EngageNY

Incredibly Useful Ratios

For Students 9th - 10th Standards
Start the exploration of trigonometry off right! Pupils build on their understanding of similarity in this lesson plan that introduces the three trigonometric ratios. They first learn to identify opposite and adjacent...
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Lesson Plan
1
1
Illustrative Mathematics

Bank Shot

For Teachers 9th - 11th Standards
Young geometers become pool sharks in this analysis of the angles and lengths of a trick shot. By using angles of incidence and reflection to develop similar triangles, learners plan the exact placement of balls to make the shot....

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