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# As further maths Vector help watch

1. I don’t know how to find the point above the base.Attachment 723242
2. Bump
3. Bump
4. (Original post by Janej77)
I don’t know how to find the point above the base.
Attachment doesn't work
5. (Original post by RDKGames)
Attachment doesn't work
Now?
6. (Original post by Janej77)
Now?
Take the flagpole base to be the origin O(0,0,0). Then the point where all 3 ropes are attached is the point P(0,0,20).

The three ropes go from this point to the points R(0,8,2), S(12,-5,3), and T(-2,6,5)

This means you can find the vectors PR, PS, PT.

You wish to find out whether the angle between PR and PS is greater than 15 degrees. So, use the result of

Similarly, you want to find the angle between PS and PT.

Similarly, you want to find the angle between PT and PR.

If all of these angles are >15 then the flagpole will be stable.
7. (Original post by RDKGames)
Take the flagpole base to be the origin O(0,0,0). Then the point where all 3 ropes are attached is the point P(0,0,20).

The three ropes go from this point to the points R(0,8,2), S(12,-5,3), and T(-2,6,5)

This means you can find the vectors PR, PS, PT.

You wish to find out whether the angle between PR and PS is greater than 15 degrees. So, use the result of

Similarly, you want to find the angle between PS and PT.

Similarly, you want to find the angle between PT and PR.

If all of these angles are >15 then the flagpole will be stable.
how do u know the point is (0,0,20)?
8. (Original post by Janej77)
how do u know the point is (0,0,20)?
Because it says it's 20m above the base.
9. (Original post by RDKGames)
Because it says it's 20m above the base.
I thought it could be (0,20,0)
10. (Original post by Janej77)
I thought it could be (0,20,0)
In a typical 3D space, the third coordinate signifies altitude. So that's the one of interest.
11. (Original post by RDKGames)
In a typical 3D space, the third coordinate signifies altitude. So that's the one of interest.
Thanks. That was the bit I was confused
12. (Original post by Janej77)
Thanks. That was the bit I was confused
Generally (and in A Level), the z axis points vertically upwards. I think this would have been made clearer if it was an exam question.

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