Spherical Triangle I know that the area for a spherical triangle is calculated as
Area $= r^2(a+b+c-\pi)=r^2E$ where $E= (a+b+c-\pi)$ is the spherical excess I was wondering why do you have to multiply by $r^2$ (the radius)?

Areas of figures with the same shape are proportional to the squares of distances involved.  Thus the area enclosed by a circle must be some constant times $r^2$.  The area of a regular pentagon whose side has length $s$ must be some constant times $s^2$.  And so on.  The constant depends on the shape.
