# Ch 43: MEGA Middle School Math: Triangle Theorems & Proofs

### About This Chapter

## MEGA Middle School Math: Triangle Theorems & Proofs - Chapter Summary

These lessons have been put together to aid in your review of the theorems and proofs used to calculate the properties of triangles. Use these lessons to prepare for MEGA Middle School Math exam questions by following along with our professional instructors as they discuss:

- Applications for similar triangles
- Triangle congruence postulates and congruence proofs
- Converse of statements
- Finding and comparing corresponding sides and angles
- Using congruence and similarity to prove relationships
- Angle-angle-side, hypotenuse angle and hypotenuse leg theorems
- Perpendicular bisector and angle bisector theorems
- Congruency of right and isosceles triangles

In addition to watching these lesson videos, you may also read the lesson transcripts that highlight in bold the key terms of this chapter. Following these lessons, be sure to test your retention of the material with the lesson quizzes.

### 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 MEGA Middle School Mathematics: Practice & Study Guide course

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