Summer School

Even though it's summer vacation, my brain isn't getting it totally off. Today I faced a quandary. I was supposed to be cleaning off the table -- which is an excellent reason to get all sorts of other things done! It's amazing how productive you can be when you're supposed to be doing something else.

Ahem.

My quandary was this: I was trying to find x,

where W, H, and L are all known.

I had a dim memory of figuring out angles and sides and such of triangles back in the dark ages of High School Geometry. So with the resident Math Genius' help I learned that all I needed to do was find this angle:

To do that, first I had to isolate this triangle,

to find angle A.
In my particular quandary,
W=14
H=18
L=27

To get to the triangle, I had to chop them up.


Since the difference between 7 and 9 is 2 (or, as Miriam would say, "The difference? 9 is bigger than 7. Duhhh.") we now know that the length of the short side, or b, is 2. Since we know that the length of side a is 9 (because I said so), and this is a right triangle, we can use our magic wands to calculate the angle A. (I always liked working with sines and cosines...)

Okay, okay, so I know this is elementary to all you other Math Geniuses out there, but I want you all to be impressed that I slogged through all this even though it's been *cough*fifteenyears*cough* since I even LOOKED at a geometry book. (Some might argue that this is proof that mathiness is in the genes... "Destiny, destiny, no escaping destiny!")

As I was saying.

After browsing and hunting around and obviously procrastinating, I finally found the most awesome website for non-mathy-geniuses like me: an online side and angle calculator! God bless the Internet. So we enter our values into the magic boxes, and voila!


We have the magic angle number: 77.47. I will annoy all the precise mathy types and round down to plain 77. Because I'm like that.

So now we go back to our trapezoid and make another triangle and plug in the values.


Once again consulting our magic 8-ball website, abra cadabra, and we learn that the new b = 6.

Now we add everything up:


6 + 7 = 13
13 x 2 =26

x = 26! Doesn't that make you feel all warm and happy inside?


So now I'm sure you're all just DYING to know WHY I just HAD to find the length of one side of a trapezoid, when I should have been cleaning my dining table. (Which did eventually get clean, by the way.) The answer is that I wanted to make a wrap skirt that fit ME and not a preteen girl with no hips. Someone told me about an online pattern, so I used it to make myself a couple wrap skirts, but was grossly dissatisfied with their fit. It was way too tight in the hips and way too large in the waist -- i.e. ill-proportioned. The formula on the website was this:

Measure your waist, and add one half (since one panel will overlap in the front).
30 + 15 =45

Then multiply by .3 (since you want to divide that measurement approximately into thirds) to find the width of the top of one panel, or W above.
45 x .3 = 13.5 (round up to 14 -- there I go again!)

Now the online pattern then went on to suggest that one multiply by .4 to find the width of the bottom hem.
45 x .4 = 18

(You also add 3 inches to everything for seam allowances, but we're going to ignore that for now.)

Now if I followed that formula, it would make the panel look like this:

which, using all that magic again, would mean that H up above would equal about 15 (trust me on this one, unless you REALLY want to do the math yourself), which fits a 33-inch hip (going backwards: 15 / .3 x .66) -- which means that to fit that skirt pattern, one would have to be proportioned like a Barbie doll!!

I happen to be a REAL woman, thus the formula to find my hem width is closer to x .6 (I kind of wonder where the pattern designer came up with her infamous x .4? I tested it out on Miriam, and her magic formula for a good fit is x .5).

So the moral of the story, kids, is to make sure you're paying attention in high school math classes -- you never know when you're going to use it later!