大象传媒

Applying Pythagoras TheoremUsing Pythagoras with coordinates

Pythagoras Theorem states that for a right-angled triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides.

Part of MathsGeometric skills

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

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

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

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

\({a^2} = 113\)

\(a = \sqrt {113}\)

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