2015-07-17 05:03:01 +0100 received badge ● Notable Question (source) 2015-07-17 05:03:01 +0100 received badge ● Popular Question (source) 2013-11-19 11:37:20 +0100 marked best answer Combine two 3d plots You have a very small typo. == is for an equation, but = is for keywords. Try this. var('x,y,z') implicit_plot3d(x^2+y^2+z^2==4, (x, -3, 3), (y, -3,3), (z, -3,3)) + implicit_plot3d(x^2+y^2+1.75^2==4, (x, -3, 3), (y, -3, 3), (z, -3, 3))  2013-11-19 11:37:20 +0100 received badge ● Scholar (source) 2013-11-19 11:37:19 +0100 received badge ● Supporter (source) 2013-11-19 08:40:42 +0100 asked a question Combine two 3d plots It's possible to combine two 2d plots in one: sum([plot(x^n,(x,0,1),color=rainbow(5)[n], figsize=3) for n in range(5)])  How can this be done for 3d plots? For example, I tried this: implicit_plot3d(x^2+y^2+z^2==4, (x, -3, 3), (y, -3,3), (z, -3,3)) + implicit_plot3d(x^2+y^2+1.75^2=4, (x, -3, 3), (y, -3, 3), (z, -3, 3))  But it generates this error: File "", line 1 SyntaxError: keyword can't be an expression