Answer:
The answer to your question is 9m
Explanation:
To find side length from an already given area, you have to take the square root. In essence, find the number that can multiply by itself to get the answer you want. In this case, we can split 81m^2 into 81 and m^2, to make our problem easier.
m^2 is equal to m*m, so the number that multiplies by itself is really easy to find. In this case, it's just m.
81 is a little bit harder. In this case, you just have to know ahead of time that 9*9 is 81, or use a calculator. For 81, the square root is 9.
Now, we split our problem, and now we put the answer together. m*9=9m, which is what I got for my answer.