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Lesson Plan
EngageNY

More About Similar Triangles

For Teachers 8th Standards
Determine whether two triangles are similar. The instructional activity presents opportunities for pupils to find the criterion needed to show that two triangles are similar. Scholars use the definition of similarity to find any missing...
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Lesson Plan
Curated OER

Triangle Side Lengths and Angles Measures

For Teachers 9th - 10th
Students identify missing sides and angles. In this geometry lesson, students use triangular theorems to identify the missing sides. They use the Pythagorean Theorem to find the different ratios of each side.
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Interactive
Curated OER

Angles in a Triangle

For Students 10th
In this geometry activity, 10th graders determine the measure or measures of the missing angle(s) in a triangle. The one page interactive activity contains four questions. Answers and hints are included. 
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Worksheet
Curated OER

Classify and Measure Angles #1

For Students 2nd - 3rd
In this angles activity, students classify and measure 2 simple angles. Worksheet is part of a site with additional activities and links.
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Worksheet
Curated OER

Triangle Fundamentals

For Students 8th - 12th
In this geometry worksheet, students observe a triangle marked with three angles and are given two measures to find the missing third measure. A second diagram is given with six angles. There are 20 questions.
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Worksheet
Helping with Math

Angles: Supplementary, Corresponding & Alternate (2 of 2)

For Students 6th - 8th Standards
In the second of two similar worksheets, anglers compute missing angles when given an alternate, supplementary, or complementary value. There are six problems to solve, but each of them requires two to four solutions. This is a nice...
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Lesson Plan
Curated OER

Angle-Side Relationships

For Teachers 9th - 12th
Students calculate the different sides and angles of a triangle. In this geometry instructional activity, students use triangular properties to define the relationship between two triangle. They identify missing angles using the interior...
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Worksheet
Curated OER

Angles and Lines: Calculate What Is Missing

For Students 6th
In this angles and lines:  calculate what is missing worksheet, 6th graders look at four geometric shapes with some information given about angles and lines and calculate the measurements that are missing.
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Lesson Plan
Utah Education Network (UEN)

Finding Missing Lengths of Similar Triangles

For Teachers 7th - 10th
Middle and high schoolers explore the properties of similar triangles. In this geometry lesson, pupils play a similarity basketball game, sketch similar triangles, and find the missing measures of similar figures. They find the height of...
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Lesson Plan
EngageNY

The Angle-Angle (AA) Criterion for Two Triangles to Be Similar

For Teachers 9th - 10th Standards
What do you need to prove triangles are similar? Learners answer this question through a construction exploration. Once they establish the criteria, they use the congruence and proportionality properties of similar objects to find...
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Lesson Plan
EngageNY

Looking More Carefully at Parallel Lines

For Students 9th - 10th Standards
Can you prove it? Making assumptions in geometry is commonplace. This resource requires mathematicians to prove the parallel line postulate through constructions. Learners construct parallel lines with a 180-degree rotation and then...
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Lesson Plan
Curated OER

My Angle on Cooling

For Teachers 5th - 8th
Students explore how the angle and distance of an object can change it's temperature. After reviewing how the position of the Earth affects the temperature of the planet, student groups design and perform an experiment to test how...
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Worksheet
Curated OER

Determine the Measure of an Angle of a Right Triangle.

For Students 10th - 11th
In this geometry worksheet, students solve word problems by finding the values of missing angles and missing sides of triangles. They review their trigonometric properties of a right triangle. There are 9 problems with an answer key.
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Worksheet
Curated OER

Geometric Shapes and Angles

For Students 10th
In this geometry instructional activity, 10th graders review polygons and solve for the missing angles of trapezoids and isosceles triangles. There are 10 questions on this instructional activity with an answer key.
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Worksheet
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Curated OER

Right Triangle Trigonometry: Evaluating Trigonometric Ratios

For Students 10th - 12th
In this right triangle trigonometry worksheet, students use trigonometric ratios to determine the length of a missing side of a triangle or to find a specified angle measurement. This four-page worksheet contains 32 problems. Answers are...
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Worksheet
Curated OER

Proving Quadrilaterals

For Students 10th
For this geometry worksheet, 10th graders identify the missing angles using the polygons sum conjecture. They measure exterior and interior angles using their angle theorems. There are 63 problems.
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Worksheet
Curated OER

Pairs of Angles Homework

For Students 9th - 10th
In this algebra worksheet, learners identify the missing angles. They use properties of angles, linear pair and vertical angles to find their missing measurement. There are 14 questions.
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Worksheet
Curated OER

Classifying Angles

For Students 10th
In this classifying angles worksheet, 10th graders solve and complete 35 various types of problems. First, they match each type of angle with its correct description. Then, students determine whether the given lines or planes are...
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Worksheet
Curated OER

Classify and Measure Angles #1

For Students 2nd - 3rd
In this angles worksheet, students classify and measure 2 simple angles. Worksheet is part of a site with additional activities and links.
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Lesson Plan
Willow Tree

Ratios and Proportions with Congruent and Similar Polygons

For Students 8th - 11th Standards
Investigate how similar and congruent figures compare. Learners understand congruent figures have congruent sides and angles, but similar figures only have congruent angles — their sides are proportional. After learning the...
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Worksheet
Curated OER

Intersecting Lines

For Students 10th
In this intersecting lines worksheet, 10th graders solve and complete 16 various types of problems. First, they find the measures of each missing angles in the diagrams shown. Then, students determine the types of angles formed in each...
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Worksheet
Curated OER

Angle and Radian Measure

For Students 9th - 10th
In this angle and radian measure activity, students find the measurement of a central angle. Students determine the speed of rotation, linear speed of a point, and radians per second. This two-page activity contains twelve problems. ...
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Worksheet
Curated OER

Measuring Segments

For Students 10th
For this measuring segments worksheet, 10th graders solve 12 different problems related to determining the measurements of various segments. First, they determine each missing measure given the information. Then, students find the value...
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Interactive
Curated OER

Try These Angles! Exploring Angles: Post Test

For Students 5th - 8th
In this angles worksheet, students answer multiple choice questions about angles on their own and angles inside shapes. Students complete 10 multiple choice questions.