1.1Drawing tools: line, polyline, circle, arc, rectangle, polygon
Time to draw. AutoCAD's basic entities are few but fundamental: the line, the polyline (a series of segments/arcs forming a single object), the circle, the arc, the rectangle. Every drawing, even a complex one, is built from these primitives.
But drawing "roughly" is not enough in technical work: you must draw to the right dimensions. This is the role of coordinate entry: absolute (X,Y from the origin), relative (@dx,dy from the last point) and polar (@distance<angle). Mastering this entry is what takes you from a sketch to a real, precise technical drawing.
Section vocabulary
- Line (LINE / L)
- Straight segment between two points. Each segment is a separate object.
- Polyline (POLYLINE / PL)
- Connected series of segments and arcs forming ONE single object: ideal for contours.
- Absolute coordinates
- X,Y position measured from the origin (0,0) of the drawing.
- Relative coordinates
- Displacement from the last point: @dx,dy (Cartesian) or @distance<angle (polar).
- Dynamic input
- Input fields that follow the cursor to enter distances and angles directly on screen.
What makes a drawing PRECISE in AutoCAD?
In practice — Drawing to the right dimensions
- Draw a line (L) by clicking two points, then do it again by typing absolute coordinates (e.g. 0,0 then 100,50).
- Draw a precise rectangle using relative coordinates: a starting point, then @200,100.
- Use polar entry: a 150 mm line at 30° → @150<30.
- Draw a polyline (PL) chaining several segments: notice it forms a single object, unlike separate lines.
Key points to remember
- Basic entities: line, polyline, circle, arc, rectangle.
- The polyline forms ONE object (contours), unlike separate lines.
- Coordinates: absolute (X,Y), relative (@dx,dy), polar (@dist<angle).
- Coordinate entry is what makes the drawing precise.
Frequently asked questions
What's the difference between a line and a polyline?
A series of LINEs creates independent segments (each one is selected and edited separately). A POLYLINE connects the segments into a single object, which is much more practical for a contour (you select it with one click, apply a width, compute its perimeter/area, offset it…). For any closed contour or continuous path, prefer the polyline.
Absolute, relative, polar: which one to use?
In practice, you mostly use the relative and the polar ones, because you usually draw "from the previous point" (a 3 m wall to the right = @3000,0 or @3000<0). Absolute is mainly used for the first point or a precise reference from the origin. Modern dynamic input makes these entries very smooth directly on screen.