Question

2. The area of a semi-circular tin plate is 19.25 cm², find its diameter.​

Answer 1

Given

• Area of semi - circular tin plate is 19.25 cm².

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To find

• Diameter of the semi circle.

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Solution

• We know that d(diameter) = 2r(radius)

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$\: \: \: \: \: \: \: \: \: \: \: \: \boxed{\tt{\bigstar{Area_{(semi-circle)} = \dfrac{1}{2} \pi r^2{\bigstar}}}}$

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$\large{\tt{\longmapsto{19.25 = \dfrac{1}{2} \times \dfrac{22}{7} \times r^2}}}$

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$\large{\tt{\longmapsto{19.25 = \dfrac{11}{7} \times r^2}}}$

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$\large{\tt{\longmapsto{r^2 = \dfrac{19.25 \times 7}{11}}}}$

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$\large{\tt{\longmapsto{r^2 = \dfrac{134.75}{11}}}}$

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$\large{\tt{\longmapsto{r^2 = 12.25}}}$

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$\large{\tt{\longmapsto{r = \sqrt{12.25}}}}$

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$\large{\bf{\longmapsto{r = 3.5cm}}}$

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Therefore,

$\boxed{\sf{\orange{d = 2r}}}$

• d = 2 × 3.5
• d = 7cm

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