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MNetters love a maths question

56 replies

noblegiraffe · 19/03/2023 11:41

Here's a lovely maths question I saw on twitter the other day.

For a Y8 class.

Bear that in mind while you're thinking WTF?

Grin

MNetters love a maths question
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Bimbleberries · 19/03/2023 12:32

Purplecatshopaholic · 19/03/2023 12:29

And it’s crap like this that makes me glad I did not take Maths further than GCSE level (despite getting an A, and having a Maths Teacher as a mother)! What on earth is the point of learning this?

It's not really about learning this as a fact ,though. And post GCSE maths isn't really much like this.

It's more of a puzzle that lets you apply what you know to a more complicated situation, and that's kind of fun when you see that a simple rule can actually let you do something quite hard like this, and kind of satisfying and fun when you work it out I didn't get it for a while, had to really think, but then I did see it. It wouldn't be something that we'd have ever been taught. The skills of problem solving, though, are generally useful in maths as well as other disciplines, so I can see why they include something like this as a puzzle for year 8

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iklboo · 19/03/2023 12:33

Just colour the small rectangle grey to match & then draw a line through the middle ☺️

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titchy · 19/03/2023 12:34

You'd have to understand the properties of a line that bisects the middle of a rectangle will always split in two equal halves

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titchy · 19/03/2023 12:34

iklboo · 19/03/2023 12:33

Just colour the small rectangle grey to match & then draw a line through the middle ☺️

Now that is thinking outside the box!

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noblegiraffe · 19/03/2023 12:34

iklboo · 19/03/2023 12:33

Just colour the small rectangle grey to match & then draw a line through the middle ☺️

Best answer.

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WinterMusings · 19/03/2023 12:39

Elephantstatue · 19/03/2023 12:17

Tell us then Qantaqa - Id just go for down the middle, a bit off centre. But then I'm a near enough kind of girl most of the time.

@Elephantstatue Are you an architect?

😂😂😂😂

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BrowniesnotBlondies · 19/03/2023 13:57

Diagonal line (cuts in half without having to exactly measure).
White triangle irrelevant?

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noblegiraffe · 19/03/2023 13:59

You need to have the same amount of grey on each side of your line so the white rectangle is relevant as it is not grey.

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BrowniesnotBlondies · 19/03/2023 14:18

Have used my brains now (ie googled, found on Twitter). I shall not spoil it for others....though I liked someone'e rephrasing

I have a tray of brownies. Someone took a random piece out of the middle. How do I share the rest equally into 2 portions.

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SertralineAndTherapy · 19/03/2023 14:20

titchy · 19/03/2023 12:34

You'd have to understand the properties of a line that bisects the middle of a rectangle will always split in two equal halves

Aha! Thank you.

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Drifta · 19/03/2023 14:33

ah cool. I didn't get it. I love that it's such a generic solution - you could place the white rectangle anywhere, including along an edge, and it would still work. Thanks for this.

One of those ones that lets kids wow their parents!

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BrowniesnotBlondies · 19/03/2023 14:37

A hint for anyone stuggling....(and it is in the question)...you can draw more than one line to help you get the answer.

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PrehistoricGarbageTruck · 19/03/2023 14:45

My dh just instantly came up with what seems to be the sensible solution (hinted at by pp)

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Greentree1 · 19/03/2023 16:03

I assume that any line going through the centre point divides a rectangle in half, so the line that goes through the centre point of both rectangles divides both in half.

True for diagonals, verticals and horizontals, and looks right, but not going to try to prove it generally!

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SertralineAndTherapy · 19/03/2023 16:07

Greentree1 · 19/03/2023 16:03

I assume that any line going through the centre point divides a rectangle in half, so the line that goes through the centre point of both rectangles divides both in half.

True for diagonals, verticals and horizontals, and looks right, but not going to try to prove it generally!

Not a formal proof, but draw a line through the middle parallel to one pair of sides.. Any other line through the middle will create symmetric shapes above and below that reference line!

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Mumoftwoinprimary · 19/03/2023 16:12

I have a Cambridge maths degree. And I only got it after reading some of the hints!

Oh - the shame!

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tiredhadenough · 19/03/2023 16:19

I'm confused!!!! Will the answer be shared?

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Piggywaspushed · 19/03/2023 16:21

What the jeff?! Just tell the rectangle thief to own up and put the stolen bit back.

Then divide in two.

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TeenDivided · 19/03/2023 16:23

tiredhadenough · 19/03/2023 16:19

I'm confused!!!! Will the answer be shared?

Draw the diagonals on the white rectangle and again on the giant grey rectangle.
Now draw a line that does from one edge to another going through the two points where the diagonals cross.

Any line through the centrepoint of the rectangle splits it in half by area. So you have split both rectangles in half so the grey area is equal on both sides.
I expect someone will draw a picture and upload it in due course.

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OneFrenchEgg · 19/03/2023 16:40

@TeenDivided I just did exactly what you said - is the blue line the divider???

MNetters love a maths question
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titchy · 19/03/2023 16:45

OneFrenchEgg · 19/03/2023 16:40

@TeenDivided I just did exactly what you said - is the blue line the divider???

Exactly.

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OneFrenchEgg · 19/03/2023 16:49

Amazing. I would never have worked that out

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Tribollite · 19/03/2023 16:58

Wow. I would have never got that.

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Nailsandthesea · 19/03/2023 17:00

Find the middle of each rectangle and then draw a line through both middles?

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Oblomov23 · 19/03/2023 17:05

Well, I wouldn't have thought of that!

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