this post was submitted on 08 Oct 2024
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[–] [email protected] 12 points 6 days ago (1 children)

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

[–] [email protected] 4 points 5 days ago* (last edited 5 days ago) (1 children)

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.

[–] [email protected] 1 points 4 days ago

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

[–] [email protected] 14 points 6 days ago (2 children)

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".

[–] [email protected] 5 points 5 days ago

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

[–] [email protected] 4 points 5 days ago* (last edited 5 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.

[–] [email protected] 11 points 6 days ago (1 children)

Either this is drawn wrong or they broke geometry

[–] [email protected] 1 points 5 days ago* (last edited 5 days ago)

The triangles aren’t drawn to scale. The middle line isn’t a 90° angle, because it isn’t specifically marked with a square angle in the corner. Triangles always add up to 180°, so the angle in the left triangle is actually 80°, not 90°.

[–] [email protected] 3 points 6 days ago

That was a good one

[–] dnick 2 points 6 days ago

The angle formerly known as twitter

[–] [email protected] 0 points 5 days ago

Heheheh the 2 triangles are having segs

[–] [email protected] 217 points 1 week ago* (last edited 1 week ago) (17 children)

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.

[–] [email protected] 69 points 1 week ago (1 children)

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.

[–] [email protected] 29 points 1 week ago (3 children)

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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[–] [email protected] 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.

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[–] Habahnow 64 points 1 week ago (14 children)

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.

[–] [email protected] 56 points 1 week ago (16 children)

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

[–] [email protected] 1 points 6 days ago

When you're finding the outside angle along the line of a triangle you don't need the inside angle tied to that outside angle if you have the other two inside angles since both straight lines and triangles total to 180 degrees.

[–] [email protected] 26 points 1 week ago (2 children)

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

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[–] [email protected] 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.

[–] [email protected] 21 points 1 week ago (7 children)

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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[–] [email protected] 49 points 1 week ago (4 children)
[–] [email protected] 67 points 1 week ago* (last edited 1 week ago) (12 children)

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....^

[–] [email protected] 1 points 6 days ago

Actually, it might be a 90 degree angle, but the shape on the left might be a quadrilateral instead of a triangle.

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[–] [email protected] 46 points 1 week ago (4 children)

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 1 points 6 days ago (1 children)

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

[–] [email protected] 1 points 5 days ago

yep. I wasn't paying enough attention

[–] [email protected] 33 points 1 week ago (1 children)

135°.

The non-right-angle is downright cheeky.

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