Current Events > UK adults stumped by Math question aimed at 7 year old girls.

(+) Yeah! (+)

This maths question was given to seven-year-old students as part of their homework, and it left lots of people on social media stumped.

Dad-of-two - Dr Kit Yates co-director of the Centre for Mathematical Biology at Bath University - shared the baffling question on his Twitter feed. He asked: "This was my daughters (7) maths homework on Monday. Can someone help me out with the answer?"

He added: "Im not being facetious here. Im genuinely not sure what I should advise her the correct answer should be."

The image shows a semi-circle in a box with the question: "True or false? This shape has two right angles. Explain your answer."

The math's lecturer's question went viral - as lots of people admitted they were stumped.

One person joked: "Someday I'd like to teach an undergraduate class titled "Central Questions in Philosophy" where the only course text is third-grade math problems."

Another suggested: "I'm going for yes, on the basis that in as much as a single angle exists for a curved line it should be 90 degrees at those two points. (ie there's no other single value that makes sense)."

A third helpfully contradicted that answer, as they replied: "I'd say no because there are curved lines but maybe I'm wrong. That seems damn tough for someone so young."

The lecturer agreed that the question was tough and said he would set the question for his university students next week.

He said: "I am in a fortunate position that meant I felt I could be used this as an opportunity to talk to my daughter about how the answer could be either true or false depending on your understanding of 'angle'.
"But I'm sure not every parent, or teacher for that matter, would have the time to delve too far into this.
"It's actually a really deep and thought-provoking question which could be used later on in school to spark conversations about infinity, tangents, calculus and many more interesting mathematical concepts, but it might not be best for seven-year-olds being homeschooled by their parents!

"I'm going to set it as a riddle for my second year University Maths students next week to see what they come up with."

He said: "As a mathematician though I am aware that we can also think about the angle between two curved lines as the angle that their tangents (the straight lines parallel to the curve at that point) would make.

What do you think CE?

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nah that ain't a right angle

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False, it has zero right angles

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That's a wrong angle

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Aiming math questions at girls is oddly specific.

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Only if you bisected it, but they haven't so

NO

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If that's the exact center of a perfect circle than at the point of intersection it would in fact be 2 right angles. The fact that the line curves over time doesn't change the actual intersection.

This is a bit like asking a kid of negative infinity + infinity is zero. A kid is going to say yes, a math major is going to say no.

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the image brings something to me.... must buy bridge constructor portal.
even though i hate bridge constructor. it falls apart every time.
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7 year olds are taught about right angles?

Just based on the age that the question is targeted to, I would say false, since they are probably taught that right angles only occur in squares/rectangles/triangles, or that they are very obvious. EDIT: Like the solution was posted above, they use the corner of the paper to fit into the shape to see how many right angles there are.

If the question was meant for adults, though, I would still say either false or lack of enough information to say. Those would only be right angles on the corners if the shape was defined as a perfect circle and the line was defined as a perfect circle, The question doesn't define shit.

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AngelsNAirwav3s posted...

7 year olds are taught about right angles?

lol obviously

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s0nicfan posted...

If that's the exact center of a perfect circle than at the point of intersection it would in fact be 2 right angles. The fact that the line curves over time doesn't change the actual intersection.

This is a bit like asking a kid of negative infinity + infinity is zero. A kid is going to say yes, a math major is going to say no.

So if that point is the middle, you're saying there is an angle? But wouldn't that area, no matter where on the circle you are, still be curved and thus not a right angle?

The two corners form right angles...and itsa 180 degree angle... so the correct answer is 4...i think

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AngelsNAirwav3s posted...

Just based on the age that the question is targeted to, I would say false, since they are probably taught that right angles only occur in squares/rectangles/triangles, or that they are very obvious. EDIT: Like the solution was posted above, they use the corner of the paper to fit into the shape to see how many right angles there are.

This seems relevant:

lol @ all the yes answers

it's "no" u dummies

I'll assume that the curvature of the half-circle does not have two points that lie along the same vertical plane, so the flat edge cannot form a straight corner.

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There are 8 right angles in that picture.

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Squall28 posted...

There are 8 right angles in that picture.

oh yeah.

JimmyFraska posted...

So if that point is the middle, you're saying there is an angle? But wouldn't that area, no matter where on the circle you are, still be curved and thus not a right angle?

There's an angle because there's an intersection. I'm saying it must be a right angle at the limit just by the basic definition of a perfect circle.

Those angles have some measure, and the exact measure of that angle is going to change depending on whether that line runs through the middle of the circle or, say, the top third.

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s0nicfan posted...

There's an angle because there's an intersection. I'm saying it must be a right angle at the limit just by the basic definition of a perfect circle.

Those angles have some measure, and the exact measure of that angle is going to change depending on whether that line runs through the middle of the circle or, say, the top third.

Wouldn't it only be a right angle at the exact point of the tangent? Can a dot be an angle?

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Squall28 posted...

Wouldn't it only be a right angle at the exact point of the tangent? Can a dot be an angle?

Which is why I said at the limit. if you assume a line is intersecting with a single point on the circle, then there isn't an angle present. The question is what is the angle between the circle and the line formed by that point and another point on the circle that is infinitely close to it? It's got to be something, or otherwise we would have to say that there are no angles in the picture at all.

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nope you can see the curve starts immediately.

at best it's like a 95 degree angle but definitely not a perfect 90.

The root issue seems to be that "just use the corner of a page!" is how it's meant to be done, but the question as given leaves that part out.

It's the ten-boxes thing all over again. We expect parents to somehow help the child arrive at a specific expected end state, but don't bother explaining the intended steps to get there.

s0nicfan posted...

If that's the exact center of a perfect circle than at the point of intersection it would in fact be 2 right angles. The fact that the line curves over time doesn't change the actual intersection.

This is a bit like asking a kid of negative infinity + infinity is zero. A kid is going to say yes, a math major is going to say no.

This is my first thought as well. Once you know how sine of 0 and 90 degrees are derived, you will always see 2 right angles in an exact half circle.

No, clearly one of those angles is situated on the left side.

Everything about this is weird.

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Obviously there is no point on the curve in which a straight line, let alone a line perpendicular to the diameter of the circle the semi circle comes from can be made. But I can see how somebody can overthink it and imagine how the closer you zoom in on the corner the closer a right angle is to appearing, and get lost on the idea that it approaches a right angle or some shit. But yea, there is simply no point on the curve blah, blah, blah.

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Seaman_Prime posted...

No, clearly one of those angles is situated on the left side.

Yeah even if I was completely ignorant of what a "right angle" was, I would assume that there aren't two right angles because surely the one on the left is actually a left angle. >_>
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If you're working out the angle between curves, you just take the tangents of the curves at the point of intersection.

So yes, at the point of intersection the angle actually is 90. But also the question is obviously not intended to dive into continuous functions, and it's meant to be a no.

You guys are thinking way too much for a supposedly third grade question

Just answer false ffs

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Woodger posted...

If you're working out the angle between curves, you just take the tangents of the curves at the point of intersection.

Is that considered a traditional right angle or is it more of an angle of trajectory? Honest question.

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Math was a mistake

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RedWhiteBlue posted...

It infinitely approaches a right angle at 89.999... Degrees. So yes, 2 right angles. A kid would likely be told no.

I'm going to maintain that a dot can't be an angle. It never reaches 90 until the tangent.

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My answer is False, but this is a trick question

I dont like the question that math question beeds to be given to no one in any school imo, only mr spock knows the answer

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I don't know what the rigorous definition of angle is, if it even exists, when dealing with one of the lines being a curve.

At most I would say that the limit of the angle is 90 degrees, if an angle can be defined at all.

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No. The angles in the circle are infinitesimally smaller than 90 degrees, and therefore not right angles.

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Trumble posted...

No. The angles in the circle are infinitesimally smaller than 90 degrees, and therefore not right angles.

This is the 0.999999~ trap. Don't fall into that.

Well the half circle has zero but the square that makes the whole thing has four. None of this includes non Euclidean.

The whole thing might just be fake like that dress.

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Obviously the answer is supposed to be false. There are other examples of kids being taught basic stuff in science, history, etc... that isn't technically true but as far as they know it is. It is interesting though, because like someone said it has to do with the limit approaching a right angle, right? I would say true because of that.

More importantly...

Darmik posted...

Aiming math questions at girls is oddly specific.

Can you elaborate on this tc? Why is this question only for girls?

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KainWind posted...

Can you elaborate on this tc? Why is this question only for girls?

It's right there in the topic title