The question said that the points of A, B and C were (-2,-3), (6,1) and (k,3) respectively, and that AB is perpendicular to BC.
It asked to work out the gradient of AB:
y2-y1 / x2-x1 = 4/8 --> 1/2.
I think that might be right but then it says to prove that the value of k equals 5. How could I do that?
Thanks for that. It was really helpful.
The next question says that the line L is parallel to BC and passes through A, asking you to figure out an equation for L:
I used the formula "y-y1=m(x-x1)", A(-2,-3) and the -2 gradient from earlier used to put into values as this:
y--3 = -2(x--2)
y+3 = -2(x+2)
y+3 = -2x-4
y+2x-7=0 [L]
Is this right? Thanks again for your help.
I'll use the slope-intercept form there then. It makes more sense! And I see how you get +7 because you need to take the 4 over to the other side, I didn't see that.
There's only one more part to the question, it says that the line intersects the y-axis at D and asks to calculate the length of CD.
Now here, I'm very stuck and not sure what formula to use. Can you help at all? If you can thanks again!