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The value of x (sh.itjust.works)
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[-] AVincentInSpace@pawb.social 11 points 6 days ago

The answer is 125 degrees but the triangle on the left has 190 degrees in it

[-] PM_Your_Nudes_Please@lemmy.world 5 points 6 days ago* (last edited 6 days ago)

Nah, the angle isn’t specified as a right angle. We can’t assume it’s 90° just because it’s drawn that way, because it isn’t drawn to scale.

Left triangle has 180° total. 60+40=100, which means that middle line is actually 80°, not 90. And since the opposite side is the inverse, we know it is 100° on the other side.

100+35=135. We know the right triangle also has 180° total, so to find the top corner we do 180-135=45. So that top corner of the right triangle is 45°, meaning x must be 135° on the opposite side.

[-] lord_ryvan@ttrpg.network 0 points 5 days ago

I mean, it's visibly an acute angle wether it's labelled as such or not.

Heheheh the 2 triangles are having segs

[-] TheGrandNagus@lemmy.world 217 points 1 week ago* (last edited 1 week ago)

What a deviously misleading diagram.

The triangle on the left isn't actually a right angle triangle, as the other angles add to 100°, meaning the final one is actually 80°, not 90°.

Therefore the triangle on the right also isn't a right angle triangle. That corner is 100°.

100+35=135°. 180-135=45°. So that's 45° for the top angle.

X = the straight line of the joined triangles (180°) - the top angle of the right triangle (45°). 180-45=135°

X is 135°, not the 125° it initially appears to be.

[-] greyfox@lemmy.world 69 points 1 week ago

It also doesn't say that the line on the bottom is straight, so we have no idea if that middle vertex adds up to 180 degrees. I would say it is unsolvable.

[-] TheOakTree@lemm.ee 29 points 1 week ago

This is what I was thinking. The image is not to scale, so it is risky to say that the angles at the bottom center add up to 180, despite looking that way. If a presented angle does not represent the real angle, then presented straight lines might not represent real lines.

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[-] GoodEye8@lemm.ee 26 points 1 week ago

I used to have teacher who deliberately made disproportionate diagrams. His reasoning was that people trust too much what their eyes see and not enough what the numbers tell them. He would've loved that diagram.

[-] frezik@midwest.social 18 points 1 week ago
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[-] tpihkal@lemmy.world 14 points 1 week ago

Leave it to the Grand Nagus to spot a clever ruse.

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[-] Habahnow@sh.itjust.works 64 points 1 week ago

All these people saying its 135 are making big assumptions that I think is incorrect. There’s one triangle (the left one) that has the angles 40, 60, 80. The 80 degrees is calculated based on the other angles. What's very important is the fact that these triangles appear to have a shared 90 degree corner, but that is not the case based on what we just calculated. This means the image is not to scale and we must not make any visual assumptions. So that means we can’t figure out the angles of the right triangle since we only have information of 1 angle (the other can’t be figured out since we can’t assume its actually aligned at the bottom since the graph is now obviously not to scale).

Someone correct me if I'm wrong.

[-] Brosplosion@lemm.ee 56 points 1 week ago

135 is correct. Bottom intersection is 80/100, 180-35-100 = 45 for the top of the second triangle. 180 - 45 = 135

[-] Leate_Wonceslace@lemmy.dbzer0.com 26 points 1 week ago

Mathematician here; I second this as a valid answer. (It's what I got as well.)

[-] PresidentCamacho@lemm.ee 14 points 1 week ago

Random guy who didn't sleep in middle school here: I also got the same answer.

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[-] TheOakTree@lemm.ee 14 points 1 week ago

You're making the assumption that the straight line consisting of the bottom edge of both triangles is made of supplementary angles. This is not defined due to the nature of the image not being to scale.

[-] NoMoreLurkingToo@startrek.website 22 points 1 week ago

Unless there are lines that are not straight in the image (which would make the calculation of x literally impossible), the third angle of the triangle in the left has to be 80°, making the angle to its right to be 100°, making the angle above it to be 45°, making the angle above it to be 135°. This is basic trigonometry.

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[-] brisk@aussie.zone 39 points 1 week ago

This is a standard way to draw geometric proofs, it's not at all unreasonable to assume straight lines alongside unrepresentative angles. It's certainly still an assumption, but a conventional one.

[-] qarbone@lemmy.world 21 points 1 week ago

I mean, the assumption shouldn't be anything about scale. It should be that we're looking at straight lines. And if we can't assume that, then what are we even doing.

But, assuming straight lines, given straight lines you find the other side of an intersecting line because of complements.

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[-] dragonfucker@lemmy.nz 49 points 1 week ago
[-] PresidentCamacho@lemm.ee 67 points 1 week ago* (last edited 1 week ago)

It pisses me off to no end that what is CLEARLY shown as a 90degree angle is not in fact 90deg, I hate it when they do that.

Also I will sadly admit this can teach people lessons about verifying the information themselves.

^GrumbleGrumbleGrumble....^

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[-] Skullgrid@lemmy.world 46 points 1 week ago

trash diagram too, the 90 degree looking center angle is actually 80 on the left, 100 on the right.

180 - (100 + 35) = y

x = 180 -y

I can't be assed to do the simple math

[-] taladar@sh.itjust.works 1 points 6 days ago

You mean the simple math of 180 - 180 is too much? Or 100 + 35?

[-] Skullgrid@lemmy.world 1 points 6 days ago

yep. I wasn't paying enough attention

[-] SomeoneSomewhere@lemmy.nz 33 points 1 week ago

135°.

The non-right-angle is downright cheeky.

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[-] tigeruppercut@lemmy.zip 17 points 1 week ago

trash diagram too

A lot of those standardized tests like SAT or GRE like to put those in (or at least they used to) on purpose. It wasn't that they couldn't render the diagrams correctly, instead they were checking for people making assumptions with information that wasn't given. To be somewhat fair I seem to recall a disclaimer that they weren't necessarily drawn accurately.

[-] taladar@sh.itjust.works 2 points 6 days ago

Often they also have multiple slightly different versions of the numbers so people don't cheat by copying their neighbor's solution but the diagram is the same.

[-] NigelFrobisher@aussie.zone 17 points 1 week ago

I like that all the comments are people discussing the diagram.

[-] celsiustimeline@lemmy.dbzer0.com 14 points 1 week ago

This is the geometry version of those stupid poorly written math equations. Engagement bait.

The real answer is always "it's unsolveable due to poor/missing notation".

[-] cucumber_sandwich@lemmy.world 6 points 6 days ago

But it's not unsolvable, just a misleading drawing...

[-] PM_Your_Nudes_Please@lemmy.world 5 points 6 days ago* (last edited 6 days ago)

It’s not unsolvable at all. The answer is x=135°. The triangles simply aren’t drawn to scale; The line between them isn’t a 90° angle, (even though it is drawn that way) because it is not specifically marked as 90° with a square angle mark.

[-] tyler@programming.dev 14 points 1 week ago

Right one does not depend on the left one. 3rd dimension for the win!

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[-] RandomStickman@fedia.io 13 points 1 week ago

C'man there's totally a 1px shift on the line. You can't just assume it's a right angle.

[-] taladar@sh.itjust.works 1 points 6 days ago

More importantly, there is enough information in the numbers alone that you don't have to rely on estimating any angles from the drawing.

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this post was submitted on 08 Oct 2024
1117 points (98.2% liked)

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