Projection of (1) on xoy plane

The projection of the hemisphere is: x 2+y 2+z 2 = a 2, provided that z=0, so it is x 2+y 2 = a 2.

The projection of a cylinder is x 2+y 2 = ax, provided that z=0.

Therefore, the projection of the common part is: x 2+y 2 = ax, z=0.

(projection on the xoz plane

The top is determined by X 2+Y 2+Z 2 = A 2 and X 2+Y 2 = AX at the same time.

De: ax+z 2 = a 2-(a)

Both sides are determined by x 2+y 2 = ax and y=0.

de:x ^ 2 = ax，x=0，x = a-(b)

The bottom is z = 0-(c)

Because it is in the xoy plane, there is another condition that y = 0-(d).

So the projection of male * * * on xoy is made up of (a), (b), (c) and (d) * * *, which is something like a rectangle.

But the top is not a straight line, but a parabola