Find the area and perimeter from (i) to (iii) semi-circles:(i) Radius of semicircle $=1.4cm$(ii) Diameter of semicircle $=7cm$ - Noon Academy

Find the area and perimeter from (i) to (iii) semi-circles:(i) Radius of semicircle $=1.4cm$ (ii) Diameter of semicircle $=7cm$

Class 10 | Frank | ICSE | Maths | Mensuration I

Find the area and perimeter from (i) to (iii) semi-circles:(i) Radius of semicircle $=1.4cm$ (ii) Diameter of semicircle $=7cm$

(i)

According to question,

Radius of semi-circle, $r=1.4cm$

Perimeter of semi-circle $=\left( \pi r+2r \right)$

$=\left[ \left( 22/7 \right)\times \left( 1.4 \right)+\left( 2\times 1.4 \right) \right]$

$=7.2cm$

Area of semi-circle $=1/2\pi {{r}^{2}}$

$=1/2\times \left( 22/7 \right)\times {{\left( 1.4 \right)}^{2}}$

$=3.08c{{m}^{2}}$

(ii)

According to question,

Diameter of semi-circle, $d=7cm$

Radius = half of the diameter of semi-circle

$r=d/2$

$r=7/2$

$r=3.5cm$

Perimeter of semi-circle $=\left( \pi r+2r \right)$

$=\left[ \left( 22/7 \right)\times \left( 3.5 \right)+\left( 2\times 3.5 \right) \right]$

$=18cm$

Area of semi-circle $=1/2\pi {{r}^{2}}$

$=1/2\times \left( 22/7 \right)\times {{\left( 3.5 \right)}^{2}}$ $=19.25c{{m}^{2}}$

i

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