+
Lesson Plan
EngageNY

Similarity and the Angle Bisector Theorem

For Teachers 9th - 10th Standards
Identifying and verifying reproducible patterns in mathematics is an essential skill. Mathematicians identify the relationship of sides when an angle is bisected in a triangle. Once the pupils determine the relationship, they prove it to...
+
Lesson Plan
EngageNY

Congruence Criteria for Triangles—AAS and HL

For Students 9th - 10th Standards
How can you prove it? Guide classes through an exploration of two possible triangle congruence criteria: AAS and HL. Learners connect this criteria to those previous learned and also explore criteria that does not work. The instructional...
+
Lesson Plan
Curated OER

Perpendicular and Angle Bisectors

For Teachers 10th
In this geometry worksheet, 10th graders solve problems that are based on the theorems associated with perpendicular and angle bisectors of a triangle.  An application on the coordinate plane is included.  The one page worksheet contains...
+
Worksheet
Curated OER

Chapter 5 Final Review Extra Problems. Triangles

For Students 10th - 12th
In this triangles worksheet, students identify the median, altitude, segment, angle bisector, perpendicular bisector and triangle midsegment of triangles.  They find the perimeter of triangles.  This three-page worksheet contains 8...
+
Lesson Plan
EngageNY

Tangent Segments

For Teachers 9th - 12th Standards
What's so special about tangents? Learners first explore how if a circle is tangent to both rays of an angle, then its center is on the angle bisector. They then complete a set of exercises designed to explore further properties and...
+
Worksheet
Mt. San Antonio Collage

Isosceles Triangles and Special Line Segments

For Students 9th - 12th Standards
Under which conditions can a triangle be classified as isosceles? High schoolers practice identifying isosceles triangles and special line segments, including angle bisectors, medians of triangles, and perpendicular bisectors of sides of...
+
Unit Plan
Curated OER

Transformations in the Coordinate Plane

For Teachers 9th - 12th Standards
Your learners connect the new concepts of transformations in the coordinate plane to their previous knowledge using the solid vocabulary development in this unit. Like a foreign language, mathematics has its own set of vocabulary terms...
+
Unit Plan
Mathematics Vision Project

Module 5: Circles A Geometric Perspective

For Teachers 9th - 12th Standards
Circles, circles, everywhere! Pupils learn all about circles, central angles, inscribed angles, circle theorems, arc length, area of sectors, and radian measure using a set of 12 lessons. They then discover volume formulas through...
+
Lesson Plan
Curated OER

Bisectors of Triangles

For Teachers 10th
In this geometry worksheet, 10th graders solve problems involving the perpendicular bisectors and angle bisectors of a triangle and their points of concurrency.  The one page worksheet contains sixteen questions.  Answers are included. 
+
Lesson Plan
EngageNY

Circles, Chords, Diameters, and Their Relationships

For Teachers 9th - 10th Standards
A diameter is the longest chord possible, but that's not the only relationship between chords and diameters! Young geometry pupils construct perpendicular bisectors of chords to develop a conjecture about the relationships between chords...
+
Unit Plan
Mathematics Vision Project

Module 3: Geometric Figures

For Teachers 9th - 12th Standards
It's just not enough to know that something is true. Part of a MVP Geometry unit teaches young mathematicians how to write flow proofs and two-column proofs for conjectures involving lines, angles, and triangles.
+
Assessment
Concord Consortium

Detective Stories

For Students 9th - 12th Standards
The truth will always come out. A short performance task has learners considering a witness statement given to a detective. They apply special line segments in triangles and Ceva's Theorem to prove that the witness is actually lying.
+
Lesson Plan
Curated OER

Ruler and Compass Constructions

For Teachers 4th - 5th
Fourth and fifth graders examine how to construct perpendicular lines and to bisect angles using rulers and compasses in this unit of lessons. They design a number of polygons using these methods.
+
Unit Plan
Mathematics Vision Project

Geometric Figures

For Teachers 10th - 12th Standards
Logical thinking is at the forefront of this jam-packed lesson, with young mathematicians not only investigating geometric concepts but also how they "know what they know". Through each activity and worksheet, learners wrestle with...
+
Lesson Plan
Curated OER

Special Segments in a Triangle

For Teachers 10th
In this geometry worksheet, 10th graders review the vocabulary associated with the special segments of a triangle and the associated points of concurrency and solve problems in which they find the indicated missing angle or segment.  The...
+
Unit Plan
Mathematics Vision Project

Circles: A Geometric Perspective

For Teachers 10th - 12th Standards
Circles are the foundation of many geometric concepts and extensions - a point that is thoroughly driven home in this extensive unit. Fundamental properties of circles are investigated (including sector area, angle measure, and...
+
Lesson Plan
Curated OER

Pedal Triangles

For Teachers 8th - 10th
Students identify the properties and theorems of triangles. In this geometry lesson, students construct angle bisectors using a compass and straight edge. They identify triangular similarity and congruency.
+
Worksheet
Curated OER

Geometry Worksheet

For Students 10th
In this geometry worksheet, 10th graders solve for the missing angles using the angles theorems. There are 3 questions asking about angle bisectors and missing angles.
+
Worksheet
Curated OER

Congruent Triangles

For Students 10th
In this congruent triangles worksheet, 10th graders solve and complete 16 different types of problems. First, they name the corresponding parts of the congruent triangles shown and draw a picture. Then, students list the five ways to...
+
Lesson Plan
Curated OER

Cabri Jr. Perpendicular Bisector of a Chord

For Teachers 9th - 12th Standards
Your learners will construct the perpendicular bisector of a chord. They use Cabri Jr. to construct a circle and a perpendicular bisector of a chord. They then measure lengths of the chords and perpendicular bisectors. Learners use...
+
Worksheet
Curated OER

Standardized Geometry Test Practice

For Students 10th
In this angles, lines and figures review worksheet, 10th graders solve and complete 33 standardized multiple choice problems. First, they use the Segment Addition Postulate to solve for a variable given an equation for each line. Then,...
+
Lesson Plan
EngageNY

Triangle Congruency Proofs (part 1)

For Teachers 9th - 10th Standards
Can they put it all together? Ninth graders apply what they know about proofs and triangle congruence to complete these proofs. These proofs go beyond the basic triangle congruence proofs and use various properties, theorems, and...
+
Lesson Plan
Curated OER

Heron's Formula

For Teachers 9th - 10th
Students use Heron's formula to calculate the area of a triangle. In this geometry lesson, students use three different methods to solve the area of a triangle. They find and construct the incentor and angle bisector of a triangle.
+
Worksheet
Curated OER

Triangle Fundamentals Homework

For Students 9th - 10th
For this geometry worksheet, students identify the missing angles of non right triangles using the angle sum theorem. They solve for the unknown using algebra. There are 21 questions.