Login

Welcome, Guest. Please login or register.

April 18, 2024, 12:24:49 pm

Author Topic: Co-ordinate Geometry + Division of Interval  (Read 469 times)  Share 

0 Members and 1 Guest are viewing this topic.

DanielSmith

  • Adventurer
  • *
  • Posts: 8
  • Respect: 0
Co-ordinate Geometry + Division of Interval
« on: January 23, 2019, 12:40:25 pm »
0
3U mathematics

Thanks :)

RuiAce

  • ATAR Notes Lecturer
  • Honorary Moderator
  • Great Wonder of ATAR Notes
  • *******
  • Posts: 8814
  • "All models are wrong, but some are useful."
  • Respect: +2575
Re: Co-ordinate Geometry + Division of Interval
« Reply #1 on: January 23, 2019, 02:03:48 pm »
+3
\[ \text{The point }P\text{ can be parametrised as }\left(t, \frac{3t-5}{2} \right).\\ \text{The point }Q\text{ can be parametrised as }\left( s, 12-s\right). \]
\[ \text{Once we have this, we can just plug straight into the ratio division formula.}\\ \text{Considering }AP:AQ = 1:2\text{ we have}\\ \begin{align*} 1 &= \frac{s+2t}{1+2}\\ 2&= \frac{(12-s) + 2\left(\frac{3t-5}{2}\right)}{1+2} \end{align*}\\ \text{You should now be able to solve these simultaneous equations.}\]
Note: Here I assume internal division, although in theory external division is also possible.

DanielSmith

  • Adventurer
  • *
  • Posts: 8
  • Respect: 0
Re: Co-ordinate Geometry + Division of Interval
« Reply #2 on: January 23, 2019, 03:17:34 pm »
+1
\[ \text{The point }P\text{ can be parametrised as }\left(t, \frac{3t-5}{2} \right).\\ \text{The point }Q\text{ can be parametrised as }\left( s, 12-s\right). \]
\[ \text{Once we have this, we can just plug straight into the ratio division formula.}\\ \text{Considering }AP:AQ = 1:2\text{ we have}\\ \begin{align*} 1 &= \frac{s+2t}{1+2}\\ 2&= \frac{(12-s) + 2\left(\frac{3t-5}{2}\right)}{1+2} \end{align*}\\ \text{You should now be able to solve these simultaneous equations.}\]
Note: Here I assume internal division, although in theory external division is also possible.

Thank you for replying.
I was able to get the right answer using your method. Q(11/5, 49/5) internally, Q(7,5) externally.