Everyday perimeter of a rectangle problems come down to one relationship between asin, sin, cos, tan, circumcircle radius and area. This calculator turns those numbers into diagonal (d), with the working shown so you can check the result rather than simply trust it.
What Is the Perimeter of a Rectangle Calculator?
The perimeter of a rectangle calculator works through asin, sin, cos, tan, circumcircle radius and area to give you diagonal (d).
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 Perimeter of a Rectangle 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 asin set to 10, sin set to 5, cos set to 2, the calculator returns diagonal (d) of 20. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out diagonal (d)?
Enter asin, sin, cos, tan, circumcircle radius and area. The calculator then works through the relationship and reports diagonal (d).
What does the perimeter of a rectangle actually calculate?
It takes asin, sin, cos, tan, circumcircle radius and area and converts them into diagonal (d) 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 asin?
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.