Deriving the Laplacian in spherical coordinates

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Homework Statement



Printed homework page on the Laplacian in spherical coordinates, showing two forms of the Laplacian formula and two spherical coordinate diagrams with x, y, z axes, r, theta and phi, and the equations x = r sin theta cos phi, y = r sin theta sin phi, z = r cos theta.

Printed homework sheet with parts (b) to (e) on spherical coordinates: showing the derivative of the unit vector r-hat with respect to theta is orthogonal to it, the theta-hat and phi-hat unit vector relations, and the gradient in spherical coordinates.

Printed worksheet on spherical coordinates: parts (f) and (g) with partial derivative identities for unit vectors, the gradient in spherical form, and the Laplacian target formula with a hint.

Homework Equations



All above.

The Attempt at a Solution



Tried the first few, couldn't get them to work. Any ideas, hopefully for each step?
 
For a, you should remind yourself of trigonometric identities involving right triangles.

For b, how long is a unit vector?