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### Course: Geometry (FL B.E.S.T.)>Unit 2

Lesson 1: Introduction to rigid transformations

# Getting ready for performing transformations

Identifying points, identifying number opposites, estimating angles, and calculating distance help prepare us to perform transformations.
All of math builds on earlier concepts, and geometry is no exception!
Let's refresh some of the earlier concepts that will come in handy as we explore transformations. We'll have links for more practice for any concept in case you would like additional review. Then we'll look ahead to how the idea will help us with transformations.

## Identifying and plotting points on the coordinate plane

### Practice

Problem 1.1
Use the following coordinate plane to write the ordered pair for each point.
PointOrdered pair
$A$$\left($
,
$\right)$
$B$$\left($
,
$\right)$
$C$$\left($
,
$\right)$

For more practice, go to Points on the coordinate plane.

### Where will we use this?

There are many ways to transform figures: using a coordinate plane, using a compass and straightedge, folding and layering translucent paper, or using geometry software. Identifying and plotting points will be a building block of transforming on the coordinate plane.
Here are a few of the exercises that build off of the coordinate plane:

## Identifying the opposite of a number

### Practice

Problem 2
Which point represents the opposite of $-3$ on the number line?

For more practice, go to Number opposites.

### Where will we use this?

Reflections across the $x$-axis or $y$-axis involve finding the opposite of a number. Rotations by multiples of $90\mathrm{°}$ about the origin also involve number opposites.
Here are a couple of the exercises that build off of number opposites:

## Estimating angle measurement

### Practice

Problem 3.1
Look at the angle shown below.
Estimate the measure of the angle.

For more practice, go to Estimate angle measures.

### Where will we use this?

We will take our estimations a step further, using positive and negative angle measures to indicate the direction and amount of a rotation. We use this skill in the Rotate points exercise.
Be careful: estimating angle measures only makes sense when our figure is to scale. It is just as important to know when not to estimate as to know when we should.

## Calculating distance with the Pythagorean theorem

### Practice

Problem 4
What is the distance between the following points?

For more practice, go to Distance between two points.

### Where will we use this?

Although translations, reflections, and rotations all preserve distance, dilation generally changes the distance between a point and the center of dilation. We will determine scale factor by comparing distances, and we will create figures with proportional side lengths to the pre-image.
Here are a couple of the exercises that build off of calculating distance:

## Want to join the conversation?

• How will this help me in life?
• Any construction project, like building a dog house.
• How will this help me when i go to the army
• u could use it 2 distract the enemy by saying bet u can't solve this problem😎
• I'm taking HS Geometry next year and am absolutely terrified
• It alright buddy just believe in yourself
• I hate when the teachers set me up on this ;(
• pongase a jalar chamaco mi ado
• what is the Pythagorean Theorem?
• side(squared) + side(squared) = Hypotenuse(squared)
• So for finding the distance between two points how will you know which one is a and which one is b when using the Pythagorean Theorem?
• It doesn't matter. The distance from a to b is the same as the distance from b to a, so either point could be either variable.
• How do you use the Pythagorean theorem and make it a correct answer? I messed up on that question and got it wrong 3 times over.