Math equation demo

The following shows an angled degree symbol: $\angle {90}^{\circ }$

$P_{wave}={\frac {\rho g^{2}h^{2}T_{e}}{6400\pi }}$
${\frac {{\vec {X}}_{0}}{P({\vec {X}}_{0})}}\nabla _{\{H,T,B,\eta \}}P({\vec {X}}_{0})=(2,1,1,1)$

In more explicit terms, the equaliser consists of an object E and a morphism eq : E → X satisfying $f\circ eq=g\circ eq$, and such that, given any object O and morphism m : O → X, if $f\circ m=g\circ m$, then there exists a unique morphism u : O → E such that $eq\circ u=m$.

A morphism $m:O\rightarrow X$ is said to equalise $f$ and $g$ if $f\circ m=g\circ m$.