# The Exterior Derivative

We’re going to derive half the identities in Vector Calculus by introducing a powerful new operator.

In the previous article, I promised that we could use Differential Forms to prove a lot of important theorems, derive a lot of identities, and evaluate some integrals in arbitrary coordinate systems.

Before we could do any of that, though, we had to introduce two operators: the wedge product ∧ and the Hodge star operator **⋆**. Introducing those operators took up the entire article, so we were only able to derive the formula for the volume element and some other formulas related to the wedge product and Hodge dual. In this article, we’re going to come up with the last operator needed to do all of Vector Calculus: the exterior derivative.

# Check Your Understanding

While we don’t have enough to derive every identity in Vector Calculus, we can still do some of the simpler ones.

## Vector Calculus in Spherical Coordinates

Derive a formula for the

- Gradient,
- Divergence,
- Curl,
- and Laplacian