# coordinate geometry question

The line L passes through the points P ( -1,2) and Q (11,8). A) Find an equation for L in the form y= mx+c, where m and c are constants. ( I'm fine with this part of the question) B) The line Z passes through the point R (10,0) and is perpendicular to L. The lines L and Z intersect at the point S. Calculate the coordinates of S ( to find the coordinates of S you equate the first equation L to the equation of the second line Z and then find the values of x and y I think? Please correct me if I'm wrong) C) Show that the length of RS is 3 square root 5 (Use formula of finding the length of a straight line)

D) Hence, or otherwise, find the exact area of triangle PQR This is the part I'm struggling with, please answer if you can Thanks

Answers

If you found m ("slope") for the first part of the question, then a perpendicular line would have (-1/m) as its slope. Does that help? Cheers

08 October 2013

You are right about the second part. Now you have S.For the area of the triangle, it helps if you picture all P Q R S points and draw the lines between them too.Then you can say PQ is the BASE of the triangle (=6sqrroot5), and SR (already calculated) is the HEIGHT.AREA triangle = (BASE X HEIGHT) divided by 2=6sqr5 x 3sqr5 x 1/2=18 x 5 x 1/2=45 amma right?

08 October 2013

lines.jpg

08 October 2013

Thanks x10000000 !!! :)I understand how to do it now, thanks for taking the time to reply back and answer the question :D

08 October 2013

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