Co-ordinate Geometry
GCSE y = mx + c where m = gradient and c = y intercept
A Level 0 = ax + by + c where a = gradient and c = y intercept
Can use either at any point but always finish with the latter equation
A Level 0 = ax + by + c where a = gradient and c = y intercept
Can use either at any point but always finish with the latter equation
Finding Gradient
m = y2 - y1
x2 - x1
x2 - x1
Need Two Co-ordinates
y1 can be either value but x1 needs to be part of the same coordinate
y1 can be either value but x1 needs to be part of the same coordinate
Finding equation of Straight Line
m = y - y1
x - x1
x - x1
Need the gradient and a co-ordinate
If both are put together then:
If both are put together then:
y - y1 = x - x1
y2 - y1 = x2 - x1
y2 - y1 = x2 - x1
Need Two Co-ordinates
Normal Gradient
The gradient of a line perpendicular, called the normal, is the negative reciprocal to the to the gradient of the original line
The sum of the two gradients always comes to -1
The sum of the two gradients always comes to -1