## Perpendicular and Parallel Lines

#### 1. What are perpendicular lines?

Two lines meeting or crossing each other at 90° are called

In the figure above, the lines AB and EF cross each other at a right angle (90°).

AB and EF are perpendicular to each other. We write it as AB

**perpendicular lines**.In the figure above, the lines AB and EF cross each other at a right angle (90°).

AB and EF are perpendicular to each other. We write it as AB

**⊥**EF.#### 2. What are parallel lines?

Two or more lines that never meet are called

In the figure above, the lines AB and EF are parallel lines.

We write it as AB // EF. We show two or more parallel lines using arrowheads.

**parallel lines**.In the figure above, the lines AB and EF are parallel lines.

We write it as AB // EF. We show two or more parallel lines using arrowheads.

#### 3. Use a set square to draw a line that is perpendicular to the line XY and passes through the point P.

**Step 1:**

Place one short side of the set square on the line XY.

**Step 2:**

Move the set square along XY so the other short side touches Point P.

**Step 3:**

Use the edge of the set square to draw a line through Point P as shown below.

In the figure above, ST

**⊥**XY.

#### 4. Use a set square to draw a line that is parallel to the line XY and passes through the point P.

**Step 1:**

Place one short side of the set square on the line XY. Then place a ruler on the other short side.

**Step 2:**

Slide the set square along the ruler until the side of the set square that was placed against XY touches Point Q.

**Step 3:**

Use the edge of the set square to draw a line through Point P as shown below.

In the figure above, ST // XY.

#### 5. Horizontal and Vertical Lines

The figure below shows a rectangular frame hung on a wall.

The lines PQ and SR are horizontal lines. They are

The lines SP and RQ are vertical lines. They are

A horizontal line and a vertical line are perpendicular to each other.

The lines PQ and SR are horizontal lines. They are

**parallel to the level floor**. All horizontal lines are parallel to each other.The lines SP and RQ are vertical lines. They are

**perpendicular to the level floor**. All vertical lines are parallel to each other.A horizontal line and a vertical line are perpendicular to each other.