I know how to find the perpendicular of a line, you just find the gradient, flip it and stick a minus in front of it but i dont know how you would work it out when it says 'that passes through the point (....) so please help
2. Sub in m and the given values for x and y; x=4, y=1
1=(1/2)*4+c therefore c=-1
3. Give the gradient m and y-intercept c in the form y=mx+c, multiplying through to simplify.
Answered Wed 7th November, 2012 @ 20:33 by Alliesweet Edited by Alliesweet on Wed 7th November, 2012 @ 20:35
Alliesweet is right, just to add on you could also use y-y1=m(x-x1), which i find quicker
just as you said, when you multiply both the gradients we get "-1" as the answer (m1*m2=-1)
therefore the gradient of the perpendicular line in this case is 1/2.
sinse we got the co ordinate where the perpendicular line passes through, we can find the equation of the line usiing (y-Y1)=m(x-X1) by substituting the co ordinates of the point in the place of Y1 & X1.
There it becomes (y-1)=1/2(x-4), we can leave it in this form however if we want to rearrange it, it becomes y-1=x/2-4/2, then y=x/2-2+1