Circumference and area of a circle questions and answers

Worked solution

1. $2 \times \pi \times 5 = 31.415\ldots$
2. $\approx 31.4$ cm

Worked solution

1. $\pi \times 16 = 50.265\ldots$
2. $\approx 50.3$ cm²

Worked solution

1. $\pi \times 5^2 = 25\pi$ cm²

Worked solution

1. $50 \div \pi = 15.915\ldots$
2. $\approx 15.9$ cm

Worked solution

1. $r^2 = 31.83\ldots$
2. $r = 5.641\ldots \approx 5.64$ cm

Worked solution

1. $\tfrac{1}{2} \times \pi \times 36 = 18\pi = 56.548\ldots$
2. $\approx 56.5$ cm²

Worked solution

1. Curved part $= \tfrac{1}{2} \times \pi \times 10 = 15.707\ldots$
2. $15.707 + 10 = 25.707\ldots \approx 25.7$ cm

Worked solution

1. Circumference $= 0.7\pi = 2.199\ldots$ m
2. $1000 \div 2.199\ldots = 454.7\ldots \approx 455$