cccc 0 Report post Posted April 29, 2016 For this question, part (e)(ii) I don't understand how the answer could be so simple. I tried a very long-winded way to prove that it was, but the answer simply says as the parameter t >0, therefore D would not lie between A and B?? Does anyone understand the logic behind this? I have also attached the mark scheme. Any comments would be greatly appreciated! Thanks! Share this post Link to post Share on other sites

thecsstudent 59 Report post Posted April 29, 2016 I think the answer is t<0 because to find the equation of the line with direction the vector AB you write it as l = A + tAB, where A is the point and AB is the vector. Which means that a point on the line that comes after A will have the coordinates of A PLUS tAB. However, since t is negative the point D is before A in the line and therefore is not on AB because it comes before A. I don't know if that makes sense. 1 Share this post Link to post Share on other sites

cccc 0 Report post Posted April 29, 2016 1 hour ago, thecsstudent said: I think the answer is t<0 because to find the equation of the line with direction the vector AB you write it as l = A + tAB, where A is the point and AB is the vector. Which means that a point on the line that comes after A will have the coordinates of A PLUS tAB. However, since t is negative the point D is before A in the line and therefore is not on AB because it comes before A. I don't know if that makes sense. Thx! Makes a lot of sense! Share this post Link to post Share on other sites