Question

please solve this its very urgent.​

Answer 1

GIVEN :–

• Area of semi-circular plate = 19.25 cm²

TO FIND :–

• Diameter = ?

SOLUTION :–

• We know that –

$\\ \implies { \bold{Area \: \: of \: \: semi - circle = \dfrac{\pi {r}^{2} }{2} }}$

• Put the values –

$\\ \implies{ \bold{19.25 = \dfrac{\pi {r}^{2} }{2} }}$

$\\ \implies{ \bold{19.25 \times 2 = {\pi {r}^{2} } }}$

$\\ \implies{ \bold{38.5 = {\pi {r}^{2} } }}$

$\\ \implies{ \bold{38.5 = { \dfrac{22}{7} \times {r}^{2} } }}$

$\\ \implies{ \bold{{r}^{2} = { \dfrac{7}{22} \times 38.5} }}$

$\\ \implies{ \bold{{r}^{2} = 12.25}}$

$\\ \implies{ \bold{r = \sqrt{ 12.25}}}$

$\\ \implies{ \bold{r = 3.5\:cm}}$

• We also know that –

$\\ \implies{ \bold{Diameter=2r}}$

$\\ \implies{ \bold{Diameter=2(3.5)}}$

$\\ \implies \large{ \boxed{ \bold{Diameter=7 \: cm}}}$

▪︎Hence , Diameter of thin plate is 7 cm.

Answer 2

Answer:

Step-by-step explanation:

${\red{\underline{\underline{\bold{Given:-}}}}}$

•Area of semi-circular plate = 19.25cm²

${\blue{\underline{\underline{\bold{To\:Find}}}}}$

•The diameter of the semi-circular plate

${\green{\underline{\underline{\bold{Answer:-}}}}}$

$\tt\pink{Formula\:used}$

• Area of semi- circle = $\frac{\pi\:{r}^{2}}{2}$

Given, Area = 19.25cm²

• Substitute the values

$\implies \frac{\pi {r}^{2}}{2} = 19.25 \\\\</p><p></p><p>\implies \pi {r}^{2} = 19.25\times 2 \\\\</p><p></p><p>\implies \pi{r}^{2} = 39.50 \\\\</p><p></p><p>\implies {r}^{2} = \frac{39.5}{\pi}\: \: \: \: (\therefore \pi = \frac{22}{7}) \\\\</p><p></p><p>\implies {r}^{2} = 39.5 \implies \frac{7}{22} \\\\</p><p></p><p>\implies {r}^{2} = 12.25 \\\\</p><p></p><p>\implies r = \sqrt {12.25} \\\\</p><p></p><p>\implies r = 3.5cm$

As we know that

Diameter = 2r

Diameter = 2 ×3.5

$\large\purple{\underline{{\boxed{\textbf{Diameter = 7cm}}}}}$