# If a semi circle has a diameter of 4cm then what is the perimeter?

Jul 1, 2018

$\approx 10.283 \text{ cm}$

#### Explanation:

$\text{perimeter } = \frac{1}{2} \pi d + 4$

$\text{that is the semi circle plus diameter}$

"color(white)(xxxxxx)=(1/2xxpixx4)+4

$\textcolor{w h i t e}{\times \times \times} = 2 \pi + 4 \approx 10.283 \text{ cm to 3 dec. places}$

Jul 1, 2018

$\left(4 + 2 \pi\right) \text{cm}$

#### Explanation:

$d = 4 \text{cm}$ - - - i
$2 r = d$ - - - ii
$\text{Perimeter"_"semicircle} = 2 r + \frac{2 \pi r}{2}$
Substitute in ii,
$\Rightarrow d + \frac{\mathrm{dp} i}{2}$
Substitute in i,
$\Rightarrow \left(4 + \frac{4 \pi}{2}\right) \text{cm}$
$\Rightarrow \left(4 + 2 \pi\right) \text{cm}$