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.

Work out the gradients of an x first before you relate it back to the graph in question

`Gradient (m) =y/x`

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

`Gradient\ of\ li\n\e\ B=1/-1=-1` 

This shows when we multiply them together `1\times-1 = -1` 

Therefore `m_A\timesm_B=-1`


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