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What do we mean by parallel line development?

Parallel line development is used to develop patterns of square, rectangular
and cylindrical shapes (**prisms**). The method divides the surface into a series
of parallel lines to determine the shape of a pattern.

The top and front views are divided into twelve equal spaces.

The parallel lines give us the chord lengths which are then transferred
to the **stretch out**, which is the circumference. This is also divided into
twelve equal spaces.

### An example of parallel development

##### Truncated cylinder

The diagram below shows parallel line development. On the left is the
development method for a truncated cylinder. On the right is the stretch
out pattern of the shape which is then transferred onto the metal.