Hello, seran!

If you can't handle Heron's Formula,

. . then you must know some Trigonometry.

Find the area of the triangle with the lengths 2.87 m, 3.69 m and 4.58 m

565 mm, 823 mm and 1.08 m . ← What are these? We have a triangle: Code:

C
o
* *
b * * a
* *
* *
* *
A * * * * * * * B
c

We are given: .$\displaystyle \begin{array}{ccc}a &=& 2.87 \\ b &=& 3.69 \\ c &=& 4.58 \end{array}$

We can find angle $\displaystyle A$ with: .$\displaystyle \cos A \:=\:\frac{b^2+c^2 - a^2}{2bc}$

Then the area is: .$\displaystyle \tfrac{1}{2}bc\sin A$

If all this is meaningless to you,

and you're really "hopless in math",

. . . . just skip the problem.