Practise the method.Example 1A circle has radius 2cm. Find its diameter, in cm.Show worked answerAnswer: 4The diameter is twice the radius: 2×2=4cm.Example 2A circle has diameter 6cm. Its circumference is kπcm. Find k.Show worked answerAnswer: 6C=πd=6πcm, so k=6.Example 3A circle has diameter 7cm. Find its circumference, in cm. Use π=3. Give an exact answer.CircleCircleCircle with diameter 7 cm. Diagram not to scale. Use the labelled measurements.d = 7 cmDiagram not to scaleShow worked answerAnswer: 21Circumference =πd.Using π=3:3×7=21cm.