Question

In spherical or cylindrical coordinate system, why we need Cartesian cordinates (X,Y,Z axis) to define theta and phi. Can we define theta and phi without using X and Y axis? If yes,plz define it.

Answer 1

Cylindrical is r, theta and z.

Answer 2

Suppose you were in a plane. Would you need x and y values if you used r and theta?

Answer 3

suppose we are assigning a position in spherical coordinate P(r,theta, phi)
but for this we will need a center or origin for, a reference line for theta and a reference plane for phi. isn't it?

Answer 4

Sure. You need to pick an origin or reference point, and you need to decide on a plane to contain r and theta, and which way will be positive values of theta from an initial value for theta. For phi you also need a reference direction in the plane of r and theta and to decide which way is positive.