Normal vector direction of space surface Space surface f (x, y, z) = 0. Its normal vector is (FX ', FY', FZ '). What is its direction? How to determine the direction of the normal vector? For example, the space curve X = x (T), y = y (T), z = Z (T), its tangent X '(T), y' (T), Z '(T) direction is consistent with the point's moving direction when t increases. Similarly, I think there should be a conclusion for the space surface! What is that?

Normal vector direction of space surface Space surface f (x, y, z) = 0. Its normal vector is (FX ', FY', FZ '). What is its direction? How to determine the direction of the normal vector? For example, the space curve X = x (T), y = y (T), z = Z (T), its tangent X '(T), y' (T), Z '(T) direction is consistent with the point's moving direction when t increases. Similarly, I think there should be a conclusion for the space surface! What is that?

Specific inward and outward may only be determined by drawing
Specific topic specific analysis
Usually, the graph of the equation f = 0 given by the title is very clear
When calculating the surface integral, we usually only need to determine the symbol at the last step, so we just need to look at the picture at the end. The time of calculating the sea color matrix has been drawn for a long time