To make a semi- circle you need to use the ARC block. Lets look at how a full circle is made first.
sprite = codesters.Circle(0, 0, 100, "blue")
(x, y, diameter, "color")
sprite = codesters.Arc(0, 0, 100, 0, 180, "blue")
(x, y, radius, start-angle, end-angle, "color")
Start-angle and End-angle are additional parameters for arc. This let's you define a portion of the circle. In the example above, a start-angle of 0 and an end-angle of 180 draws the top half of a circle and starting at 180 and ending at 360 draws the bottom half of the circle.
For examples visit our Codesters How to Use ARC Project