# 2.5 Angle Relationships

## Investigation #1

1. Use the angle tool to measure one linear pair of angles in the diagram below.
2. Use the arrow tool the click and drag point D to change the angle measures.
3. Complete the questions below the figure based on your observations.

## Use this figure for Investigation #1 and Investigation #2.

## Observation

Which of the following statements is always true about the linear pair of angles?

## C-1 The Linear Pair Conjecture

If two angles form a linear pair, then they are _____.

## Investigation #2

1. Use the arrow tool to select and then delete one of your 2 angle measures.
2. Use the angle tool to measure the angle that is vertical to the angle measure that is left.
3. Click and drag point D to change the angle measures.
4. Complete the questions below based on your observations

## Observation

Which of the following statements is always true about the pair of vertical angles?

## C-2 Vertical Angles Conjecture

If two angles are vertical angles, then they are _____.