# IM Geometry U1L20 Transformations, Transversals, and Proof

- Author:
- Sarah Davit

- Topic:
- Geometry

## 20.1 Figure A

What is the measure of angle x, in degrees? (Just type the number.)

## 20.1 Figure B

What is the measure of angle x, in degrees? (Just type the number.)

## 20.1 Figure C

What is the measure of angle x, in degrees? (Just type the number.)

## 20.1 Figure D

What is the measure of angle x, in degrees? (Just type the number.)

## 20.2

Translate lines AE and CD by the directed line segment from B to C. The image points should be labeled appropriately as A', B', etc.
This is easiest if you set yourself up to translate all points at once.
STEPS TO DO THIS:
1) Draw a vector from B to C.
2) Click the transformations button and select the "translate by vector" tool.
3) Click and drag to highlight ALL points on both lines.
4) Click the vector from B to C to complete the translation.
5) Use the line tool to draw line A'E'.

Explain your reasoning.

Identify congruent angles. For each pair of congruent angles that you find, explain how you know the angles are congruent.

## 20.3

Rotate line AE by 180° around point C. The image points should be labeled appropriately as A', B', etc.
It is a little tricky to get the applet to cooperate for this, so we will need to rotate each point one at a time!
STEPS TO DO THIS:
1) Click the transformations button and select the "rotate around point" tool.
2) Click point A, then point C. This will rotate point A around center C. Enter the angle (180 degrees).
3) Click point B, then point C. This will rotate point B around center C. Enter the angle (180 degrees).
4) Click point D, then point C. This will rotate point D around center C. Enter the angle (180 degrees).
5) Click point E, then point C. This will rotate point E around center C. Enter the angle (180 degrees).
6) Use the line tool to draw line A'E'.

Explain your reasoning.

Identify congruent angles. For each pair of congruent angles that you find, explain how you know the angles are congruent.