this post was submitted on 08 Oct 2024
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[–] [email protected] 49 points 1 month ago (2 children)
[–] [email protected] 67 points 1 month ago* (last edited 1 month ago) (4 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] 13 points 1 month ago (1 children)

Geometry diagrams in math problems should never be assumed to be to scale

[–] [email protected] 2 points 1 month ago* (last edited 1 month ago)

Yes obviously. But it still irritates me as someone who does geometry for a living.

[–] [email protected] 13 points 1 month ago* (last edited 1 month ago) (2 children)

I get you, but it doesn't clearly indicate the angle in the middle at the base as much as it suggestively waggles its eyebrows towards 90⁰, it could just as easily be 89.9999999999999⁰, although upon zooming in, you can see the line does shift one pixel over on its way up. You simply can't trust any of the angles as 90⁰ unless it's got the ∟ symbol (that's the official unicode) or you've measured them yourself, and with that one pixel off-set, it's decidedly not 90⁰. That's why you have to do the math.

[–] [email protected] 8 points 1 month ago* (last edited 1 month ago) (2 children)

The internal angles of a triangle always add up to 180⁰, therefore the one pixel offset is irrelevant because the unlabelled angle is, despite what the image suggests, ~~60~~ 80⁰.

[–] [email protected] 4 points 1 month ago (2 children)

Assuming you're talking about the triangle on the left, it's 80⁰: 180 - 60 - 40 = 80. The other two unlabeled angles are 100⁰ and 45⁰ respectively. None of the unlabelled angles are 60⁰.

[–] [email protected] 2 points 1 month ago

The shape on the left might be a quadrilateral instead of a triangle, with a vertex at the same place as the top vertex of the shape on the right.

[–] [email protected] 1 points 1 month ago

Yes I meant 80 lol, thanks

[–] [email protected] 2 points 1 month ago

It's enough to say it's "CLEARLY" not 90⁰.

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

That's just what I said but more into the weeds on the detail.

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

Another way to look at it is that it is simply a representation of an object. We don't need to visualize the angles, as the values to the other asks are given. We just need the geometry of the object represented so we can calculate the value of the unlabeled angle. Given that the geometry of the objects is represented as triangles, we can infer that all sides are straight lines, regardless of the type of space the object occupies.

[–] [email protected] 1 points 1 month ago

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

[–] [email protected] 6 points 1 month ago (2 children)

Assuming these are straight lines.

[–] [email protected] 1 points 1 month ago

Even if they are straight lines, if that's a 2d projection of something on a non-flat 3d surface, it can also change the way the angles fit together.

[–] [email protected] 1 points 1 month ago

If these aren't straight lines, drag has no idea what the answer is and thinks it might be impossible to tell.