An inscribed semi-circle cannot touch all the four sides of a square. It can touch at most 3 sides of a square. You need to draw at least 3/4 th of the inscribed circle to touch all the four sides.
TO draw a full inscribed circle inside a square:
1. Mark the mid points E, F, G and H respectively of the sides AB, BC, CD, and DA of the square.
2. Join the mid points of the opposite sides, ie., draw EG and FH.
3. Mark the intersection of EG and FH as the center O of square.
4. Now draw a circle with the center O and radius EO or HO or GO or FO.
5. The inscribed circle will touch the sides exactly at E, F, G and H.
You can draw the inscribed circle between E, F, G and H, and stop at H. Then it is drawn to 3/4th of total, but it touches all four sides.