POLYLINE Deep-Dive

Draw connected geometry as one object using PLINE options.

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Learning objective

By the end of this lesson you can draw connected line and arc segments as a single polyline using the PLINE command and its options.

What POLYLINE is

PLINE creates a polyline — a single object made of connected straight and/or curved segments. Unlike LINE, every segment is part of the same object.

Why and when you use it

Use PLINE whenever you need a closed shape, a single editable boundary, or a path with mixed line+arc segments — boundaries, hatches, sections, outlines.

Where to find it in the AutoCAD interface

Ribbon: Home tab → Draw panel → Polyline button.
Menu: Draw menu → Polyline.
Command line: Type PLINE and press Enter.
Alias / shortcut: PL (then Enter).

Key vocabulary

Polyline: A connected sequence of line and arc segments treated as one object.
Vertex: A point where two segments of a polyline meet.
Arc segment: A curved part of a polyline, created with the A option mid-command.
Width: A polyline can have a non-zero thickness — set with the W option.

Before you start

Press F8 to enable ORTHO for clean horizontal/vertical segments.
Turn OSNAP on so vertices land on real geometry.
Have a sketch or plan of the shape you want to draw.

Step-by-step instructions

1
Start the PLINE command
2
Click the start point
3
Draw straight segments
4
Add a curved segment with the Arc option
5
Close the polyline

Visual reference

Common mistakes & fixes

Using LINE when you needed a single closed shape.
Fix: Restart with PLINE so the result is one polyline you can HATCH or EXTRUDE.
Forgetting to type C to close.
Fix: Type C, Enter on the last prompt — don't manually click back to the start point.
Mixing Arc and Line options and getting confused.
Fix: Read the command line — it always tells you which mode you're in.

Troubleshooting

Pressing Enter early ended the polyline.Show

Cause: Enter ends PLINE at any point.

Fix: Press Ctrl + Z to undo and resume — or restart with PLINE.

My polyline has visible width I didn't want.Show

Cause: The W option was set earlier in the command.

Fix: Restart PLINE, or use PEDIT → Width 0 to clear it.

Practice exercise

Draw an L-shape with POLYLINE and close it

Type PL, Enter. Click a start point.
Type @100,0 Enter, @0,50 Enter, @50,0 Enter, @0,50 Enter, @-150,0 Enter.
Type C, Enter to close.

Success looks like: A closed L-shaped polyline you can select with a single click.

Pro tips & related commands

Pro tips

Inside PLINE type W to set a non-zero width — useful for arrows and emphasis lines.
Inside PLINE type U to undo just the last segment without leaving the command.
Use PEDIT to convert old LINE chains into a polyline after the fact.

Related commands

PEDIT(PE)
Edit, join, smooth or change width of an existing polyline.
EXPLODE(X)
Break a polyline back into individual segments.
SPLINE(SPL)
Draw a smooth curve through control points.

Lesson quiz

0/2 correct

Score at least 2/2 to unlock lesson completion.

1. Inside PL, which option closes the polyline back to start?

2. REC asks for…

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EXTRUDE OFFSET + MIRROR

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