Question

find the circumference and area of a semicircle whose radius is 7.7
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Answer 1

Step-by-step explanation:

Circumference of circle=2πr

2×22/7×7.7=48.4

Answer 2

$given \: that \: \\ r = 7.7 \: cm \\ \\ we \: know \: that \\ \\ c(semicircle) = \frac{2.\pi.r}{2} = \pi \: r \\ \\ c(semicircle) = \frac{22}{7} \times 7.7 \\ \\ c(semicircle) = \frac{22}{7} \times \frac{77}{10} \\ \\ c(semicircle) = \frac{22 \times 11}{10} = \frac{242}{10} \\ \\ c(semicircle) = 24.2 \: cm$

$now \\ ar(semicircle) = \frac{1}{2} \times \pi \: {r}^{2} \\ \\ ar(semicircle) = \frac{1}{2} \times \frac{22}{7} \times ({ \frac{77}{10} })^{2} \\ \\ ar(semicircle) = \frac{11}{7} \times \frac{77}{10} \times \frac{77}{10} \\ \\ ar(semicircle) = \frac{11}{1} \times \frac{11}{10} \times \frac{77}{10} \\ \\ ar(semicircle) = \frac{121 \times 77}{100} \\ \\ ar(semicircle) = \frac{9317}{100} \\ \\ ar(semicircle) = 93.17 \: {cm}^{2}$

Hence, circumference of the given semicircle is 24.2 cm and its area is 93.17 cm²