The perimeter of a right-angled triangle is 72 cm. The lengths of its sides are in the ratio 3 : 4 : 5 Work out the area of the triangle.

Draw the triangle - recognising that it is a right angled trianglefind the scale factoruse the formula: 0.5 x base x height = area To find the scale factor you must divide the total perimeter by the sum of the ratios: 72/(3+4+5) = 6Then substitute the scaled base and height into the formula: 0.5 x (4 x 6) x (3 x 6) = 216 cm^{2Note: remember to always put units (exam technique)}