Do you know, that… ?

If you want to relate the lengths of the sides of a rectangle, you can use an equation. Most people will surely do that…

But there is a better method.

To understand it better, see the sketch below. To establish the proportion 1/3 I draw three collinear segments of equal length. If I relate the length of any of them to the length of the vertical segment – I will get the length dependence 1/3.

In practice to do this, best to draw construction line following an existing line the right number of sections. Then I frame all the lines at the bottom – it will be four segments and I remove this redundant line (long).

Now, holding down CTRL, I add a vertical segment to the selection and select the relationship Equal. note, that this method can arbitrarily divide sketches into the appropriate number of segments.

Below is a breakdown by ratio 1/2 – here it was enough to draw one line connected with the center of the lower segment.

This method will also work in the case of. circles, it is enough to properly condition the auxiliary lines drawn along the radius.