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# GCSE Maths Help and Chat Thread watch

1. (Original post by notnek)
Where did you get 5 from?

The first step is to use the fact that the area is 42 to find the length of the base. Have you done this?
5 is part of the pythagorean triple, 5,12 and 13

and no how would I do this?
2. (Original post by CraigBackner)
5 is part of the pythagorean triple, 5,12 and 13

and no how would I do this?
Yes but you only know that one of the sides is 12 so you can't assume that the other two sides are 5 and 13 - the triangle sides may not be a pythagorean triple. If you knew two of the sides were 5 and 12 then you could assume that the third must be 13.

The area of a triangle = 1/2 x base x height.

You know this is equal to 42 and you know the height is 12. So what is the base?
3. (Original post by notnek)
Yes but you only know that one of the sides is 12 so you can't assume that the other two sides are 5 and 13 - the triangle sides may not be a pythagorean triple. If you knew two of the sides were 5 and 12 then you could assume that the third must be 13.

The area of a triangle = 1/2 x base x height.

You know this is equal to 42 and you know the height is 12. So what is the base?
ok i see and working it out the base is 7 and then what to I do next?
4. (Original post by CraigBackner)
ok i see and working it out the base is 7 and then what to I do next?
Note that the triangle is isosceles.
5. (Original post by CraigBackner)
ok i see and working it out the base is 7 and then what to I do next?
Draw a vertical line down from A to divide the triangle into two right-angled triangles. These triangles have lengths 12 and 3.5 (half the base). If you find the top angle in this right-angled triangle then you can double it to get x.
6. (Original post by _gcx)
Note that the triangle is isosceles.
The base of the isosceles is 7 but what can I do with it
7. (Original post by CraigBackner)
The base of the isosceles is 7 but what can I do with it
You are able to split it into two congruent triangles, per notnek.
8. (Original post by notnek)
Draw a vertical line down from A to divide the triangle into two right-angled triangles. These triangles have lengths 12 and 3.5 (half the base). If you find the top angle in this right-angled triangle then you can double it to get x.
(Original post by _gcx)
You are able to split it into two congruent triangles, per notnek.
Ohh I see and thanks for helping!

Jane records how many millimetres of rain fall each month in her garden.

In February, there was 16 mm more rain than in January.
In march, there was 5 mm more rain than in February.
The total amount of rain for January, February and March was 172 mm.
Work out the amount of rain in January
10. (Original post by Zxrxh)

Jane records how many millimetres of rain fall each month in her garden.

In February, there was 16 mm more rain than in January.
In march, there was 5 mm more rain than in February.
The total amount of rain for January, February and March was 172 mm.
Work out the amount of rain in January
I had this question for my term test. Okay so we need to find out how much rain there was in January but we don't know so let rain of January be "x".
In february there was 16mm more rain so the expression would be x+16
In march there was 5mm more rain than in February so the expression would be (x+16)+5.
Then we know that the total amount of rain was 172 so add all the expressions together..
x+x+16+(x+16)+5 = 172
Then rearrange for x and then u would have the answer!
No ratios needed xD!
11. (Original post by NothingButWaleed)
I had this question for my term test. Okay so we need to find out how much rain there was in January but we don't know so let rain of January be "x".
In february there was 16mm more rain so the expression would be x+16
In march there was 5mm more rain than in February so the expression would be (x+16)+5.
Then we know that the total amount of rain was 172 so add all the expressions together..
x+x+16+(x+16)+5 = 172
Then rearrange for x and then u would have the answer!
No ratios needed xD!
i thought it was ratio lool thanks btw i now get it
12. (Original post by Zxrxh)
i thought it was ratio lool thanks btw i now get it
No worries!
13. This is just out of interest: has anyone looked at, any A-level material? It's something that I'd recommend if you're interested in maths as a whole.

Pete records all his maths test scores.
Each score is a mark out of 100.

After 9 tests his mean score is 59
After 10 tests his mean score is 58.5
After 11 tests his mean score is 60

Work out the difference between his scores on the 10th and 11th tests.
15. (Original post by Zxrxh)

Pete records all his maths test scores.
Each score is a mark out of 100.

After 9 tests his mean score is 59
After 10 tests his mean score is 58.5
After 11 tests his mean score is 60

Work out the difference between his scores on the 10th and 11th tests.

If you still need help then let us know in this thread.
16. (Original post by notnek)

If you still need help then let us know in this thread.
i still dont understand it
17. (Original post by notnek)

If you still need help then let us know in this thread.
18. (Original post by Zxrxh)
The difference between scores on two different tests out of 100 can't be more than 100...

What part of that thread do you not understand?
19. (Original post by Zxrxh)
No, can you post your working?
20. (Original post by RDKGames)
The difference between scores on two different tests out of 100 can't be more than 100...

What part of that thread do you not understand?
all of it

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