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# please tell me how to work these out watch

1. how do you work this out....
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2. so if you have similar shapes you need to look for a length scale factor. once you have found it you can use it to work out the missing measurement.
3. (Original post by the bear)
so if you have similar shapes you need to look for a length scale factor. once you have found it you can use it to work out the missing measurement.
how do you work that out???
4. (Original post by jesusjessica15)
how do you work that out???
so you divide a measurement on the big version of the shape by the corresponding measurement on the small version.
5. I'm pretty sure the last question was in my maths GCSE paper last year so let me give it a shot:
We know the width of the rectangle is 4 times the radius, which is 128 mm.
For the height, there is some overlap between the circles so we can't just say it's 4 x the radius . The way to get around this is by drawing an equilateral triangle between the centres of each circle, with each side having the length of 64mm, twice the radius. If we draw a vertical line down the middle of the triangle, that's its height, which we can calculate using the Pythagoras theorem as being the square root of 64 squared minus 32 squared (c squared minus a squared equals b squared). We can do this because the line down the middle of the equilateral triangle creates two right angled triangles with side lengths 32 and 64 mm. Anyway, doing this calculation gives the result 32root3. So that plus the radius times two gives us the total height of the square (draw this whole thing on paper if you don't get why that is), giving us 64+32root3.
Now if we multiply that by the width, which we have already calculated to be 128, we get 15286.48, which to 3 significant figures is 15300. Don't forget the mm squared at the end.

Anyway, hope this helped
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6. (Original post by Fblaze1)
I'm pretty sure the last question was in my maths GCSE paper last year so let me give it a shot:
We know the width of the rectangle is 4 times the radius, which is 128 mm.
For the height, there is some overlap between the circles so we can't just say it's 4 x the radius . The way to get around this is by drawing an equilateral triangle between the centres of each circle, with each side having the length of 64mm, twice the radius. If we draw a vertical line down the middle of the triangle, that's its height, which we can calculate using the Pythagoras theorem as being the square root of 64 squared minus 32 squared (c squared minus a squared equals b squared). We can do this because the line down the middle of the equilateral triangle creates two right angled triangles with side lengths 32 and 64 mm. Anyway, doing this calculation gives the result 32root3. So that plus the radius times two gives us the total height of the square (draw this whole thing on paper if you don't get why that is), giving us 64+32root3.
Now if we multiply that by the width, which we have already calculated to be 128, we get 15286.48, which to 3 significant figures is 15300. Don't forget the mm squared at the end.

Anyway, hope this helped
thank you so much
7. still don't get question 1and 2
8. For question 1, you know the shapes are similar, so if the bigger shape is 3 times as wide (which it is, since its width is 3x and the smaller one has a width of x) , it's also gonna be 3 times as long. That means 27 =3(x+3) since 27 is the bigger length and it's gotta be 3 times the smaller length, which is x+3. Anyway 3(x+3)=3x+9. 27=3x+9, take away 9 from both sides, 18 = 3x, divide both sides by 3, x = 6. The width is 3x, so the answer is 3*6, which is 18.
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