Practise the method.Example 1A circle has diameter 5cm. Find its circumference, in cm. Use π=3. Give an exact answer.CircleCircleCircle with diameter 5 cm. Diagram not to scale. Use the labelled measurements.d = 5 cmDiagram not to scaleShow worked answerAnswer: 15Circumference =πd.Using π=3:3×5=15cm.Example 2A circle has radius 3cm. Find its area, in cm2. Use π=3. Give an exact answer.CircleCircleCircle with radius 3 cm. Diagram not to scale. Use the labelled measurements.r = 3 cmDiagram not to scaleShow worked answerAnswer: 27Area =πr2.Using π=3:3×32=27cm2.Example 3A trapezium has parallel sides 5cm and 9cm, and perpendicular height 6cm. Find its area, in cm2.TrapeziumTrapeziumTrapezium with parallel sides 5 cm and 9 cm, perpendicular height 6 cm. Diagram not to scale. Use the labelled measurements.5 cm9 cm6 cmDiagram not to scaleShow worked answerAnswer: 42Area = ½ ×(sum of parallel sides)× height =(5+9)×26=42cm2.