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# Coordinate Geometry watch

1. How do i attempt this type of questions ? (Coordinate Geometry Pure1 CIE)

https://gyazo.com/642868d38bef566474540f90b6998b82
2. [full solution removed]
3. (Original post by Jian17)
How do i attempt this type of questions ? (Coordinate Geometry Pure1 CIE)

https://gyazo.com/642868d38bef566474540f90b6998b82
Well, what's the one piece of information that you need before you work out the coordinates of A and B?
4. For the second part of the question, the gradient of the perpendicular line is 1/-2. Find the equation of this line using point P and find point C. Midpoint is the sum of the coordinates of P and C divided by 2. Then show that for the midpoint, y=x.
5. (Original post by JohnCena927)
For the second part of the question, the gradient of the perpendicular line is 1/-2.
Are you sure?

Note the gradient of a line multiplied by gradient of its perpendicular is -1.
6. (Original post by RDKGames)
Well, what's the one piece of information that you need before you work out the coordinates of A and B?
Uhmm... The equation of the line?

EDIT: Oh wait, you use the point-slope form of line formula right?
7. (Original post by Jian17)
Uhmm... The equation of the line?
Yeah, find it
8. (Original post by RDKGames)
Yeah, find it
y - y1 = m ( x - x1)

y - 2t = -2 (x - 3t)

y = -2x + 8t

Do I find points A and B now ?
9. (Original post by Jian17)
y - y1 = m ( x - x1)

y - 2t = -2 (x - 3t)

y = -2x + 8t

Do I find points A and B now ?
Yes.
10. (Original post by RDKGames)
Yes.
I use cover up method:

2x = 8t
x = 4t

y = 8t

Points equal (I think):

(4t, 0) (0, 8t)

How do i find the area of triangle in terms of t now?
11. (Original post by Jian17)
I use cover up method:

2x = 8t
x = 4t

y = 8t

Points equal (I think):

(4t, 0) (0, 8t)

How do i find the area of triangle in terms of t now?
Well your triangle is defined by three points, O, A, and B. You found two of the three, and the other one is regarded as the origin. So just draw a quick sketch of the configuration of your points on a plane, then it should be obvious how to find the area.
12. (Original post by RDKGames)
Well your triangle is defined by three points, O, A, and B. You found two of the three, and the other one is regarded as the origin. So just draw a quick sketch of the configuration of your points on a plane, then it should be obvious how to find the area.
(8t * 4t) / 2

= 16t^2 ?
13. (Original post by Jian17)
(8t * 4t) / 2

= 16t^2 ?
Yes.

I get the impression that you're unsure of any step you take in a simple procedure like this for some reason. It's literally as simple as that.

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