|
Area = π×r2 Area and Circumference of a Circle r - radius Circumference = π×d d - diameter From the picture we seethat the radius r=6cm, sowe can easily find area, byusing the area formula: A=π×r2=πx62=π×36=113.1cm2 (1 d.p.) Calculate Area of this Circle 6cm For number π, please usecalculator or substitute π≈3.142 From the picture we see that the radius r=6cm, but for circumference we need diameter, but of course d=2r, so diameter here will be d=2 x 6cm=12cm and now we can easily find circumference, by using the formula: C=π×d=πx12=37.7cm (1 d.p.) Calculate Circumference of this Circle diameter For number π, please usecalculator or substitute π≈3.142 6cm A=π×r2=π× = cm2 Calculate Area of this Circle Remember r2=r x r For number π, please usecalculator or substitute π≈3.142 5cm Round the answer to 1 decimal place C=π×d=π× = cm Calculate Circumference of this Circle diameter For number π, please usecalculator or substitute π≈3.142 Remember d=2 x r 5cm Length of the Arc and Area of the Sector Asector = angle/360 x πr2 Arc Length of Arc = angle/360 x πd This is formula for the area of the wholecircle, so to find thearea of the sector multiply it by thefraction angle/360. Remember d = 2 x r This is formula for the circumeferenceof the whole circle, so to find length ofthe arc we need to multiply it by thefraction angle/360. |