Write a program to evaluate the area of a triangle given the lengths of its sides using Heron's Formula $1.$

Here is an outline:

$1.$ Get the three side lengths from the user $($which might have decimal values$)$: a$,$ b$,$ c$.$

$2.$ Check to ensure that the sides are valid for a triangle. Importantly, the sum of the lengths of any

two sides must be larger than the length of the third side $($you must check all three sides this way$).$

$3.$ Calculate the semiperimeter $($s$)$:

$4.$ Calculate the area:

You must format the output to have two decimal places $($even if they are both $0),$ and round if necessary.

For example:

Enter the length of side a: $3$

Enter the length of side b: $4$

Enter the length of side c: $5$

The area is $6\mathrm{.}00$