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Using Pythagoras with coordinates

We can also use Pythagoras to find the distance between two points.

Example

If A has coordinates (3, 4) and B has coordinates (10, 12), calculate the length of AB.

Answer

Plot the coordinates onto a graph.

Graph with co-ordinates A (3, 4) and B (10, 12)

Join up A and B to show the line AB then form a right-angled triangle.

Graph with points A (3, 4) and B (10, 12) forming a right-angled traingle of 7 x 8

\({a^2} = {b^2} + {c^2}\)

\({a^2} = {8^2} + {7^2}\)

\({a^2} = 64 + 49\)

\({a^2} = 113\)

\(a = \sqrt {113}\)

\(a = 10.6\,units\,(to\,1\,decimal\,place)\)