Question

answer it please question is in the attachment help plz ​

Answer 1

For the semicircles with diameter 21 cm:

$diameter = ab = 21 cm \\ radius = \frac{21}{2} = 10.5cm \\ area \: of \: the \: semicircle \: with \: radius \: 10.5 = \frac{1}{2} \pi \: {r}^{2} \\ a = \frac{1}{2} \times \frac{22}{7} \times 10.5 \times 10.5 \\ a = \frac{11}{7} \times \frac{105}{10} \times \frac{105}{10} \\ a = \frac{121275}{7 \times 100} \\ a = \frac{17325}{100} \\ a = 173.25 \: {cm}^{2}$

Now, C is the centre. Therefore, AC=CB=10.5 cm

Radius=10.5÷2=5.25 cm

$area = \frac{1}{2} \pi \: {r}^{2} \\ a = \frac{1}{2} \times \frac{22}{7} \times \frac{525}{100} \times \frac{525}{100} \\a = \frac{6063750}{14 \times 10000} \\ a = \frac{433125}{10000} \\ a = 43.3125 {cm}^{2}$

Area of the semicircle ADC=Area of the circle BCE= 43.3125 cm²

Now, required area is:

$area \: of \: shaded \: portion = 173.25 + 43.3125 - 43.3125 \\ area \: of \: shaded \: portion = 173.25 {cm}^{2}$

Hence, your answer is 173.25 cm².