Step 1) Create a 30 mm horizontal line with its right endpoint on the origin.

Step 2)  Add a point to the line, then use then use the midpoint constraint so that it is a midpoint.

Step 3) Make a 3 point arc starting at the midpoint and centered on the left end of the line segment:

Step 4) Dimension radius to 15

Step 5)  Create an inscribed hexagon using the polygon tool

Step 6)  Remove some parts of the hexagon using the cut tool:

Step 7) Make a vertical and a horizontal lines  as shown below. Note they are dimensioned.

Step 8)

Done now go onto “1st 3d shapes”