Whether you are estimating on the spot or checking a result somebody else gave you, the right cylinder calculator is the quickest way to get from radius (r) and longest diagonal (d) to base surface area (a_b).
What Is the Right Cylinder Calculator?
The right cylinder calculator works through radius (r) and longest diagonal (d) to give you base surface area (a_b).
It is aimed at the case where you know the method but not the arithmetic: schoolwork, a quick check on a worked example, or a figure that needs to be right first time.
How the Right Cylinder Works
Each step is applied in order and depends only on the values before it, which makes it possible to follow the calculation rather than take it on trust.
If you are working through the same problem by hand afterwards, compare the intermediate values. That is where a mistake usually shows itself.
Checking Your Own Working
Round sensibly as you go and keep the full precision in the calculator. Rounding too early is the most common way of getting a right method to give a wrong answer.
Where a result should be a whole number, such as a count, check it against the constraint that produced it. A fraction of a person is a sign that something upstream needs revisiting.
A Worked Example
Working through an example, with radius (r) set to 10, longest diagonal (d) set to 5, the calculator returns base surface area (a_b) of 628.31853. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out base surface area (a_b)?
Enter radius (r) and longest diagonal (d). The calculator then works through the relationship and reports base surface area (a_b).
What does the right cylinder actually calculate?
It takes radius (r) and longest diagonal (d) and converts them into base surface area (a_b) using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter radius (r)?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Do I have to fill in every field?
Only the fields a particular result depends on. If you leave one blank, the results that need it simply show a note instead of a number, and everything else still works.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.