SharedTutoring-Nikki-20180606.sagewsOpen in CoCalc
# 7.4.1
f(x,y) = x^2+y -2
f(0.5,0.5)
plot3d(f,(x,0.4,.6),(y,0.4,0.6)) + point3d([0.5,0.5,-1.25], size = 20, color = "red")
# Yep, curved surface looks like plane when you zoom in!

-1.25000000000000
3D rendering not yet implemented
# 7.4.3
# cutting plane for Y = 2 intersecting surface Z = X^2/2 - Y^2/4 - 4
# Z = X^2/2 - 2^2/4 - 4 = X^2/2 - 1 - 4 = X^2/2 - 5
var("X")
plot(X^2/2 - 5,(X,-2,2), axes_labels = ["X","Z"])

X