# AutoCAD coordinates

> How to type points in AutoCAD: absolute, relative and polar coordinates, a line of a given length at an angle, and polar tracking. Practise them free online.

Every point a command asks for can be picked on the drawing or typed. Typed, a point is two numbers, X and Y, separated by a comma, and where they are measured from depends on how you write them: from the origin, from the last point, or as a length and an angle from it. MellowCAD reads them as AutoCAD does with dynamic input on, its default. Each section draws one figure and shows its history.

## Absolute coordinates

Measured from the origin, `0,0`. The first point a command asks for is read this way: `20,10` is 20 along X and 10 along Y. After it, dynamic input reads a typed point from the last one, so a point measured from the origin takes `#` before it: `#120,10`.

A triangle, each corner measured from the origin.

```text
Command: LINE
Specify first point: 20,10
Specify next point or [Undo]: #120,10
Specify next point or [Undo]: #70,80
Specify next point or [Close/Undo]: C
```

## Relative coordinates

Measured from the last point: how far to go along X, then along Y. After a command's first point, that is what a typed point means, and the history writes it with `@` before it, as the command line reads it: `100,0` is 100 to the right of the last point, `-50,70` 50 back and 70 up. Typed with `@` yourself, a point is relative wherever you type it.

The same triangle, each corner measured from the one before.

```text
Command: LINE
Specify first point: 20,10
Specify next point or [Undo]: @100,0
Specify next point or [Undo]: @-50,70
Specify next point or [Close/Undo]: C
```

## Polar coordinates

A length and an angle, measured from the last point: `100<0` goes 100 along X, `60<120` goes 60 at 120°. Angles are measured from the X axis, anticlockwise: 90° is up, 180° left and 270°, or -90°, down. The history writes them with `@` too.

Three sides, each a length and an angle from the end of the last.

```text
Command: LINE
Specify first point: 0,0
Specify next point or [Undo]: @100<0
Specify next point or [Undo]: @60<120
Specify next point or [Close/Undo]: @40<210
Specify next point or [Close/Undo]:
```

## A line at an angle

To draw a line of a given length at a given angle, type the end as polar coordinates, `100<30`. Or hold the angle first: type `<30` and Enter, and the next point stays on that direction, on the cursor's side; then type the length, `100`.

A line held to 30°, then given its length, 100.

```text
Command: LINE
Specify first point: 0,0
Specify next point or [Undo]: <30
Angle Override: 30
Specify next point or [Undo]: 100
Specify next point or [Undo]:
```

## Polar tracking

With polar tracking on, `F10` or its button on the status bar, the cursor shows a guide at every multiple of its angle, set from that button's menu, and a typed length goes along the guide. The tooltip says how far and at what angle the cursor is.

Polar tracking at 30°: its guide, and the distance and angle at the cursor.

```text
Command: LINE
Specify first point: 0,0
```

## What next

- [Exercises](https://mellowcad.com/docs/exercises.md) that are typed from start to finish: [an L bracket](https://mellowcad.com/docs/exercises/l-bracket.md) with relative coordinates, [a plot of land](https://mellowcad.com/docs/exercises/plot-of-land.md) with polar ones and [a block in isometric](https://mellowcad.com/docs/exercises/isometric-block.md) along the isometric angles.
- `LINE`'s own page, and [getting started](https://mellowcad.com/docs/getting-started.md) for the command line's first steps.