# Using TeX Notation 3

Note: You are currently viewing documentation for Moodle 2.3. Up-to-date documentation for the latest stable version is available here: Using TeX Notation 3.

## Geometric Shapes

There are two ways to produce geometric shapes, one is with circles and the other is with lines. Each take a bit of practice to get right, but they can provide some simple geometry. It may be easier to produce the shapes in Illustrator or Paint Shop Pro or any one of a number of other drawing packages and use them to illustrate your lessons, but sometimes, some simple diagrams in Moodle will do a better job.

## Circles

Circles are easy to make.

 Circles are easily created, and only needs a number to determine how large the circle is. To create the circle use $$\circle(150)$$. This makes a circle of 150 pixels in diameter.

## Creating Arcs

Arcs are also easy to produce, but require some additional parameters. The same code structure used in circles create the basic shape, but the inclusion of a start and end point creates only the arc. However, notice where the 0 point is, not at the true North, but rather the East and run in an anti-clockwise direction.

 $$\circle(120;90,180)$$ $$\circle(120;0,90)$$ $$\circle(120;180,270)$$ $$\circle(120;270,360)$$

This structure breaks down into the \circle command followed by the diameter, not the radius, of the circle, followed by a semi-colon, then the demarcation of the arc, the nomination of the start and end points in degrees from the 0, East, start point. Note that the canvas is the size of the diameter nominated by the circle's parameters.

## The \picture Command

Using circles and arcs as shown above is somewhat limiting. The \picture command allows you to use a frame in which to build a picture of many layers. Each part of the picture though needs to be in its own space, and while this frame allows you to be creative, to a degree, there are some very hard and fast rules about using it.

All elements of a picture need to be located within the picture frame. Unexpected results occur when parts of an arc, for example, runs over the border of the frame. (This is particularly true of lines, which we will get to next, and the consequences of that overstepping of the border can cause serious problems.)

The \picture command is structured like:

  \picture(100){(50,50){\circle(200)}}
\command(size of frame){(x co-ordinate, y co-ordinate){\shape to draw(size or x co-ordinate, y co-ordinate)})


NOTE: The brace is used to enclose each set of required starting point coordinates. Inside each set of braces, another set of braces is used to isolate each set of coordinates from the other, and those coordinates use their proper brackets and backslash. Count the opening and closing brackets, be careful of the position,