The problem is stated-
Do the following two sets of points have the same cardinality and if so, establish a bijection:
A line segment of length four and half of the circumference of radius one (including both endpoints).
My reasoning is they do have the same cardinality and my bijection is a picture in which I drew a horizontal line and a semicircle under it (separated by approx. 2cm with the semicircle's open side facing down). At what would be the center of the circle made by the semi-circle I drew a point P. I then drew lines vertical from the original horizontal line to point P. This shows, goes my reasoning, that for every point on the line there is a corresponding point on the semi-circle.
My question is is this drawing enough to show a bijection or do I need to do more?
Thank you for your thoughts.