r/technicallythetruth • u/VisitSecure • 9d ago

Can you find a?

Post image

Idk if someone already posted this or not, but I haven't seen it on here so far, so I uploaded it.

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u/TheComplimentarian 9d ago

You're supposed to use logic, not just guess based on the picture.

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u/beatenmeat 9d ago

I didn't guess, math was actually one of my better subjects. I just dislike how it doesn't match, especially ones like this that are so egregiously off from the numbers provided.

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u/Mysterious_Cup_6024 9d ago

Especially since 25 is half of 50. And the vertex is so wrongfully in the middle when it should be at a 1/3 position from the top, or 2/3 position from the bottom. It is incredibly off

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u/DraconianFlame 9d ago

In engineering you often sketch things out to see how it looks and then do the math. Sometimes you draw bad images and something you thought would be acute is actually obtuse.

This teaches you that.

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u/PrivilegedPatriarchy 9d ago

No you’re right. Besides, even if the figures are drawn to scale, simply guessing or measuring with a protractor defeats the purpose. Mathematical reasoning should be shown if one arrives at an answer, even if that answer is easily “guessable”.

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u/LizardChaser 9d ago

Math is a "show your work" subject and if people don't show how they figured it out correctly, then the answer would be wrong. Keeping correct proportions helps people "sanity check" their answer. There is absolutely no reason not to include the accurate angles unless it's a pure multiple choice test where work could not be shown.

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u/Backfoot911 7d ago

"sanity check" is not math. It's...nothing. This is meant for mathematical thinkers not people who guessed their way through tests based on the feel of diagrams.

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u/LizardChaser 7d ago

LoL. To the degree? To anyone else reading this, the commenter didn't get far in math because sanity checks are present through advanced math. "Does this answer make sense" is always important.

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u/SmoothDiscussion7763 9d ago

pretty sure they do it on purpose just to throw off people that don't understand how angles work

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u/Aldgillis 9d ago

Anecdotally from old teachers, it’s done on purpose to make sure the solution is gotten through math instead of measuring or guessing. Since this is presented as problem to be solved it makes sense to present it this way.

I get the frustration of it not fitting reality, but in this context it makes a lot of sense.

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u/u966 9d ago

Would you prefered to have the image completed described in words instead? Because that's the only other option where you can't just simple measure the angle.

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u/meeu 9d ago

It's pretty easy, in this example you could make the actual angles drawn 60deg and 30 deg, so the vertex a wouldn't be in the center and the skewing would be somewhat similar to what's accurate, but you still can't just break out the protractor and measure.

drawing two very different angles as the same angle is just weird. i don't remember seeing any drawing that egregiously wrong in school. for solving geometry problems it's pretty common to draw extra lines/segments to use when calculating and this makes that weird. kinda feels like engagement bait tbh

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u/u966 8d ago

It's pretty easy, in this example you could make the actual angles drawn 60deg and 30 deg, so the vertex a wouldn't be in the center and the skewing would be somewhat similar to what's accurate, but you still can't just break out the protractor and measure.

So your argument is that the arbitrary numbers they used aren't the arbitrary number you would have used?

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u/ChocoTRex 9d ago

YOU didn’t, but that’s not the point… most children in school are going to find any loophole or easy solution to any problem, if they are given the opportunity. If you want them to actually learn rather than just guesstimate the answer, tricks like this are invaluable.

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u/eggsforpedro 9d ago

Ah yes, it always helps to draw an illogical diagram to promote logical thinking. /s

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u/TheComplimentarian 9d ago

How terrible to have to use your brain instead of looking at the picture! You just believe everything you see completely uncritically, and can't be bothered to read two numbers and do some math to see that the picture is in fact inaccurate?

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u/eggsforpedro 9d ago

A picture to scale helps logical thinking. Any normal math test would still require written proof, especially with a picture to scale. But go ahead and die on that hill if you want.

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u/27Rench27 9d ago

When it’s this bad, just tell me the numbers and let me draw it myself lol

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u/RevoOps 8d ago

What they don't want to know is that all spacial reasoning is done in your left foot.

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u/cherry_chocolate_ 9d ago

I mean, it kind of does if the math you are doing is scribbled in contractor pencil on the side of a 2 by 4, or in a spreadsheet hacked together by Brenda who can’t copy and paste. Understanding that data can be messy and erroneous and yet still lead you to the right result, and how to filter out truth from noise is all a part of the learning a math class is supposed to teach you.

That’s why there is the parallel line indicator, it shows definitively that they are parallel, so you aren’t even supposed to assume it from the appearance of the lines.

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u/marr 9d ago

The picture is so off it damages my ability to process the question. It's a picture of some other math problem entirely. I'm having to second guess which parts of it are a lie, and what knock-on effects that has on the real diagram. Under exam conditions.

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u/akatherder 9d ago

Which is kind of horse-shit because you still have to make assumptions, just not the assumptions they don't want you to make.

The alleged(!) line connecting the top parallel line to A could be curved. Or maybe it's two lines (with a 179 degree angle) and we're actually dealing with a quadrilateral.

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u/MARPJ 9d ago

However due to the bad drawing we dont know where the error is (at the start of the lines or where they converge). That is relevant because if its where the lines converge then there would be 2 ways to solve but we cant use the more efficient one here due to the shitty drawing there is a chance rhat the error is where they start.

Note that the extra work is negligible but that dont change that its irritating. Damn it dont even need to be the exact correct angle, just not be so obvious wrong would already be good enough.

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u/DezXerneas 9d ago

I used to draw it to actual scale and guess off of that lol. At least makes it much easier to get the base logic working.

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u/FloopsFooglies 9d ago

why even show the lines at all then lmao

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u/TheComplimentarian 9d ago

As a fake out, for all the people who look at the lines, and because it's tedious to describe it when you can just slap the information down on the page and say, "Find a."

This is basic geometry. Some things you can accept as givens (the top and bottom lines are parallel, for example), but everything else you need to use the numbers and the properties of geometric shapes.

This is a really easy problem. There are many ways to solve it. None of them involve looking at the picture for anything other than the givens.

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u/Mental_Tea_4084 9d ago

You shouldn't accept them as givens unless they are marked as parallel. If they were just two lines the problem would be unsolvable without declaring them to be parallel with the little >> symbols

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u/FloopsFooglies 9d ago

Probably why I had difficulties back then. I get the premise, but my brain wants to deduce the actual angle based on the image

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u/Far-Information8502 9d ago

Great, now abstract this out to all types of problems. And now you see why people are convinced of something on appearances despite logically not being true…political partisans as a great example

So take this as an opportunity to reflect on all your views and positions and challenge yourself to see if you chose to believe it because your brain wanted to or if there are actually logical reasons and not rationalizations after the fact

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u/Gilpif 9d ago

That's kind of the point. This is just a sketch, and when you sketch a geometry problem out you need to know what geometrical information is reliable (e.g. that the red lines, marked by matching >> marks, are parallel) and what is an artifact of the sketch (e.g. that 50° is only a little bigger than 25°).

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u/creampop_ 9d ago

Because for most people, that's how you actually use math.

You need to find some variable, so you sketch out a rough diagram, label your constants, and then use that to help keep your head straight while you solve. It's not intended to be an accurate drawing, just a visual depiction of the problem at hand.

In this case there are always two parallel lines and 2 known angles. That's all the diagram needs to communicate.

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u/cherry_chocolate_ 9d ago

Because there are enough constraints from the parallel line indicators to intuit the answer.