# Ch 43: ORELA Middle Grades Math: Triangle Theorems & Proofs

### About This Chapter

## ORELA Middle Grades Math: Triangle Theorems & Proofs - Chapter Summary

Use the lessons in this chapter to review the processes for solving mathematical problems that involve triangles. Prepare for the ORELA Middle Grades Math exam through videos that cover:

- Similar triangles
- Congruence postulates
- Congruence proofs
- Converse of a statement
- Transformations in corresponding figures
- Proving relationships
- Angle-Angle-Side Theorem
- Hypotenuse Angle Theorem
- Hypotenuse Leg Theorem
- Perpendicular Bisector Theorem
- Angle Bisector Theorem
- Congruency of right triangles
- Congruency of isosceles triangles

The video lessons in this Triangle Theorems & Proofs chapter are presented by knowledgeable instructors who present their material in fun and informative ways. You can also complete the multiple-choice quiz at the end of each video to test your understanding of key points and take the end-of-chapter test to help you figure out if you are ready to move on to the next chapter.

### ORELA Middle Grades Math: Triangle Theorems & Proofs Objectives

The ORELA Middle Grades Math exam is computer-based. It includes 150 multiple-choice questions that are designed to assess the knowledge of prospective teachers seeking an endorsement for teaching basic math to middle school students. The 255-minute test includes questions come from four main content areas:

- Number sense and operations
- Algebra and functions
- Measurement and geometry
- Statistics, probability and discrete mathematics

The properties, proofs and theorems related to triangles would be included within the measurement and geometry content, which makes up about 25% of the test questions. You must earn a score of 225 or higher to pass the exam.

### 1. Applications of Similar Triangles

Similar triangles are used to solve problems in everyday situations. Learn how to solve with similar triangles here, and then test your understanding with a quiz.

### 2. Triangle Congruence Postulates: SAS, ASA & SSS

When we have two triangles, how can we tell if they're congruent? They may look the same, but you can be certain by using one of several triangle congruence postulates, such as SSS, SAS or ASA.

### 3. Congruence Proofs: Corresponding Parts of Congruent Triangles

Congruent triangles have congruent sides and angles, and the sides and angles of one triangle correspond to their twins in the other. In this lesson, we'll try practice with some geometric proofs based around this theorem.

### 4. Converse of a Statement: Explanation and Example

Just because a conditional statement is true, is the converse of the statement always going to be true? In this lesson, we'll learn the truth about the converse of statements.

### 5. Similarity Transformations in Corresponding Figures

Watch this video lesson to learn how you can tell if two figures are similar by using similarity transformations. Learn how to find the corresponding sides and angles and then how to compare them.

### 6. How to Prove Relationships in Figures using Congruence & Similarity

In this lesson, we'll look at similar and congruent figures and the properties that they hold. We will then look at how to use these properties to prove relationships in these figures in various examples.

### 7. Practice Proving Relationships using Congruence & Similarity

In geometry, if two shapes are similar they have the same shape but different sizes, while two congruent shapes have the same shape and size. In this lesson, you will learn how to prove that shapes are similar or congruent.

### 8. The AAS (Angle-Angle-Side) Theorem: Proof and Examples

When trying to find out if triangles are congruent, it's helpful to have as many tools as possible. In this lesson, we'll add to our congruence toolbox by learning about the AAS theorem, or angle-angle-side.

### 9. The HA (Hypotenuse Angle) Theorem: Proof, Explanation, & Examples

In this lesson, we'll learn about the hypotenuse angle theorem. With this theorem, we can prove two right triangles are congruent with just congruent hypotenuses and acute angles.

### 10. The HL (Hypotenuse Leg) Theorem: Definition, Proof, & Examples

In this lesson, we'll learn about the hypotenuse leg theorem. This theorem enables us to prove two right triangles are congruent based on just two sides.

### 11. Perpendicular Bisector Theorem: Proof and Example

Perpendicular bisectors are multifunctional lines. They're not only perpendicular to the line in question, they also neatly divide it into two equal halves. In this lesson, we'll learn about the perpendicular bisector theorem.

### 12. Angle Bisector Theorem: Proof and Example

The angle bisector theorem sounds almost too good to be true. In this lesson, we set out to prove the theorem and then look at a few examples of how it's used.

### 13. Congruency of Right Triangles: Definition of LA and LL Theorems

In this lesson, we'll learn two theorems that help us prove when two right triangles are congruent to one another. The LA theorem, or leg-acute, and LL theorem, or leg-leg, are useful shortcuts for proving congruence.

### 14. Congruency of Isosceles Triangles: Proving the Theorem

Isosceles triangles have two equal sides. Are the base angles also equal? In this lesson, we'll prove how this is true. We'll also prove the theorem's converse.

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### Other Chapters

Other chapters within the ORELA Middle Grades Mathematics: Practice & Study Guide course

- ORELA Middle Grades Math: Basic Arithmetic Operations
- ORELA Middle Grades Math: Solving Math Word Problems
- ORELA Middle Grades Math: Properties of Numbers
- ORELA Middle Grades Math: Estimating & Rounding
- ORELA Middle Grades Math: Number Theory
- ORELA Middle Grades Math: Roots & Radical Expressions
- ORELA Middle Grades Math: Exponents & Exponential Expressions
- ORELA Middle Grades Math: Scientific Notation
- ORELA Middle Grades Math: Simplifying Whole Number Expressions
- ORELA Middle Grades Math: Integers
- ORELA Middle Grades Math: Rational Numbers
- ORELA Middle Grades Math: Introduction to Fractions
- ORELA Middle Grades Math: Operations with Fractions
- ORELA Middle Grades Math: Introduction to Decimals
- ORELA Middle Grades Math: Operations with Decimals
- ORELA Middle Grades Math: Percents
- ORELA Middle Grades Math: Money & Consumer Math
- ORELA Middle Grades Math: Number Patterns & Sequences
- ORELA Middle Grades Math: Properties of Functions
- ORELA Middle Grades Math: Graphing Functions
- ORELA Middle Grades Math: Negative Numbers
- ORELA Middle Grades Math: Absolute Value
- ORELA Middle Grades Math: Inequalities
- ORELA Middle Grades Math: Factoring
- ORELA Middle Grades Math: Monomials & Polynomials
- ORELA Middle Grades Math: Writing Algebraic Expressions
- ORELA Middle Grades Math: Basic Algebraic Expressions
- ORELA Middle Grades Math: Algebraic Distribution
- ORELA Middle Grades Math: Writing & Solving One-Step Equations
- ORELA Middle Grades Math: Writing & Solving Two-Step Equations
- ORELA Middle Grades Math: Simplifying & Solving Rational Expressions
- ORELA Middle Grades Math: The Coordinate Graph
- ORELA Middle Grades Math: Linear Equations
- ORELA Middle Grades Math: Systems of Linear Equations
- ORELA Middle Grades Math: Rates, Ratios & Proportions
- ORELA Middle Grades Math: Measurements
- ORELA Middle Grades Math: Perimeter & Area
- ORELA Middle Grades Math: Polyhedrons & Geometric Solids
- ORELA Middle Grades Math: Symmetry, Similarity & Congruence
- ORELA Middle Grades Math: Properties of Lines
- ORELA Middle Grades Math: Angles
- ORELA Middle Grades Math: Triangles
- ORELA Middle Grades Math: Similar Polygons
- ORELA Middle Grades Math: The Pythagorean Theorem
- ORELA Middle Grades Math: Quadrilaterals
- ORELA Middle Grades Math: Circles
- ORELA Middle Grades Math: Circular Arcs & Measurement
- ORELA Middle Grades Math: Transformations
- ORELA Middle Grades Math: Data & Graphs
- ORELA Middle Grades Math: Statistics
- ORELA Middle Grades Math: Data Collection
- ORELA Middle Grades Math: Samples & Populations
- ORELA Middle Grades Math: Probability
- ORELA Middle Grades Math: Sets
- ORELA Middle Grades Mathematics Flashcards