Mammoth Memory

Perpendicular lines


Two lines are perpendicular if you multiply the gradients of the two lines together and the
result is -1.

To remember this formula work out what the slopes of an X would be.


`Gradient (m) =y/x`

`Gradient\ of\ li\n\e\ A=1/1-1`

`Gradient\ of\ li\n\e\ B=1/-1-1` 

This shows the connection between lines with gradients 1 and -1.

When we multiply them together `1\times-1 = -1` 

Therefore `M_a\timesM_b=-1`


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