Silly Questions Thread

[TrueTears]

np

[the.watchman]

np

+1

[TrueTears]

ok.

[Aqualim]

Another question;

Given that A is (-8,2) and B is (-6,10);
Find the coordinates of P, where P   AB and AP : PB = 2 : 1

[brightsky]

Ok so the two points A and B are in the 3rd quadrant.

The X-coordinates for each of them are -8 and -6 respectively.

We are looking to divide the line in 3 parts in respect to the x-axis.

If we were to draw in the lines and , we would find that the distance between (-8,0) and (-6,0) is . So if we divide that by three, we get: So when we plot these lines on the line AB, the points would be and respectively, with and being their y coordinates. Now, AP:PB = 2:1, so clearly P has to be the point , which is

The equation of the line AB is easily found by:



Now to find the y-coordinate of P, just sub in the x-coordinate.







So the coordinates of P is

Hope this is right. :p

[Aqualim]

Ok so the two points A and B are in the 3rd quadrant.

The X-coordinates for each of them are -8 and -6 respectively.

We are looking to divide the line in 3 parts in respect to the x-axis.

If we were to draw in the lines and , we would find that the distance between (-8,0) and (-6,0) is . So if we divide that by three, we get: So when we plot these lines on the line AB, the points would be and respectively, with and being their y coordinates. Now, AP:PB = 2:1, so clearly P has to be the point , which is

The equation of the line AB is easily found by:



Now to find the y-coordinate of P, just sub in the x-coordinate.







So the coordinates of P is

Hope this is right. :p

Apparently the answer is or as the answer on the sheet states

[brightsky]

woops, I need to work on my arithmetic. :p

The equation of the line AB is .

So the y-coordinate is:







So the coordinates are

[Aqualim]

ok thanks, but what does the 'AP:PB = 2:1' part mean?

[the.watchman]

It basically means that that AP is twice the length of PB

[brightsky]

ok thanks, but what does the 'AP:PB = 2:1' part mean?

Its the ratio between the lines AP and PB.

The line AB is one whole line. P is a point on that line somewhere in the middle of A and B such that the line AP is two times the length of PB.

EDIT: What the.watchman said. :p

[the.watchman]

ok thanks, but what does the 'AP:PB = 2:1' part mean?

Its the ratio between the lines AP and PB.

The line AB is one whole line. P is a point on that line somewhere in the middle of A and B such that the line AP is two times the length of PB.

Well said!

[Aqualim]

Thanks, so how did you know that the points were in the third quandrant? wouldn't that be the 2nd quadrant (top left hand) seeing as the x point is negative whilst the y point is positive (-8,2)....

[superflya]

[brightsky]

Thanks, so how did you know that the points were in the third quandrant? wouldn't that be the 2nd quadrant (top left hand) seeing as the x point is negative whilst the y point is positive (-8,2)....

Woops, another mistake. :p Yeah it's in the second quadrant. Doesn't make a difference though.

[Aqualim]

Thanks, so how did you know that the points were in the third quandrant? wouldn't that be the 2nd quadrant (top left hand) seeing as the x point is negative whilst the y point is positive (-8,2)....

Woops, another mistake. :p Yeah it's in the second quadrant. Doesn't make a difference though.

Alright so dividing it by three has no correlation with the quadrant? then how did you know to divide it by three, or would you divide by three in any case? lol sorry for all these questions