Why do I need to learn math?


Elite member
I recently heard conversation by a young model enthusiast who stated "Why do I have to learn math in school, I'll never use it".

Personally I have always found that real world examples tend to validate the learning experience.

If you are a builder, maker etc., you most certainly will use math to various degrees. In fact I would guess that most of you already know that. But here is something that could be used as a STEM demonstration that is a simple and practical, but effective, use of trigonometry.

(To make things easier, we'll just work in degrees and ignore the use of radians).

Example 1 (top)
Example 2 (bottom)
View attachment 219435


How much dihedral does your 36" wing have?

Place the wing on a table with one side resting on the table. A triangle is formed between the table, the lower wing surface and the wingtip height from the table.

The adjacent side is half of the wingspan. 18 inches.
The opposite side is the height of the bottom of the tip to the table. 0.63 inches
To solve we will use the arc tangent (inverse) function.

atan(opposite / adjacent)

atan(0.63 / 18.0)

atan( 0.035 ) = 2.00

The answer is 2.00 degrees of dihedral.


You want to have 3 degrees of total dihedral in your wing, how high should the tip be when the wing halves are joined?

Assume a 40 inch wing span. Again we will use the tangent function, since we are still using the opposite and adjacent sides, but this time we have an angle supplied.

tan(dihedral) * (wingspan/2)

tan(3) * 20 = 1.047

The answer is to raise the wingtip 1.047 when joining the halves.

The arctan function is available on the Windows calculator in "Scientific" mode under "Trigonometry" when 2nd is depressed. (tan-1)
Ensure that the mode is in DEG.

The irony does not escape me that the example drawings were done in CAD and solved the equations!!!
thanks for the explanation but you just gave me a headache by trying fallowing it.


Elite member
I remember my old days in high school, when you had trouble understanding some problems, and you would pass by a math teacher's class when school was over. and you would walk in and ask for help even if it was not your math teacher. they would put down their bag and would say take a seat, he would get stuck until 7pm with 15 kids in class. some of the parent's would stop by with pizza, those were the days. some teacher's would make it hands on by making a project around school. sorry got carried away


New member
Oh, I like it so much to hear from youngsters "Why do I have to learn ..." and after years they have problems with further studies or another. I was a good student and I was good at math, too) Children sometimes do not understand that they should learn what they are taught at school, because this is the basis


New member
I can say that in the application of my hobbies, I use lots of trigonometry, and even algebra frequently, but aside from some math problems, and one exercise in abstracts to define pi to an arbitrary number of digits, I haven't needed calculus for the past 35 years. Still, it remains a skill that I could probably brush up on quickly enough if I had the need, and I am aware of what type of problem it could be used to solve, or solve more accurately.

Still, not knowing *how* to do stuff closes doors that you may one day want open.


CEO Flite Test
How about this problem that I am currently working on as another example:
The following 3D printed model has a printed weight of 500g with the CG at 48% aft of the nose of the 60 cm fuselage. If you place a 60g motor 95% aft in the fuselage, will a 2200 mAh LiPo have enough sliding room in front of the wing to allow for a CG range between 10 and 25 percent of the wing chord without adding additional weight? You would of course need to include all of your servos and other equipment for the estimate. While you could work this out by putting weights on a paint stirrer and balance it on a dowel, I would argue setting up a quick spreadsheet to see if this model is even worth considering would save a lot of time and heartache.

View attachment 219717
This can be solved by a sum of moments equation.


Elite member
I my career, I used an HP12C financial calculator for 20+ years figuring out leasing, present value, future value, payments, interest etc. much easier than dong the math by pencil and paper. The calculator has all the "smarts" to find the answers, BUT you had to learn how to use the calculator!

I would think it valuable to teach a few formulas (area, volume etc.) and how to input these into a spreadsheet. I recently dusted off the Pythagorean theorem in order to figure out if a wing would fit in the back of my truck. There is an immediate practical application.