AS level	Pure Maths C1 --------------------- Co-ordinates This is all about the points on a graph, curves, tangents, gradients and normals.	A Revision Aid
Be careful with the co-ordinates question. It is usually the first queston and you need you to remember a lot of formulas.  If you are not careful you can get bogged down and the time will run away with you. I got in a tangle in the mocks and before I knew it I had spent over 30 minutes on the first question. A disaster !!	What you need to know is how to calculate the following The distance between two points - this is based on pythagorus If you have the co-ordinates of two points (x1,y1) and (x2,y2) then the line between them is the hypotenuse of a right-angled triangle and is therefor equal to √(x2-x1)2 + (y2-y1)2 Example Find the length of line AB with co-ordinates (-3,0) and (1,3) length AB = √ ((1--3)2 + (3-0)2) = √ (16 +9) = √ (25) = 5 To calculate the gradient of two points of a line you would use y2-y1/x2-x1 To calculate the equation of a line when you know 1 point and the gradient you would use y-y1=m(x-x1) To calculate the equation of a line when you know both points but not the gradient you would use y-y1/x-x1 = y2-y1/x2-x1	notes A "normal" is another name for a perpendicular line from a tangent.
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