I need to use piecewise functions, and I have no idea how to do this.

So far I have this for the round head of the pumpkin:

Y1= squareroot(40-Xsquared)

Y2= -squareroot(40-Xsquared)

window is just standard.

I need triangles for eyes and a nose. I need to know how to make short lines. Can anyone steer me in the right direction for formulas for this?

Thanks.