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
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