Answer:
a) D [tex]\dfrac{\pi d}{2}+d[/tex]
b) 20 cm
Step-by-step explanation:
a) circumference of circle = [tex]\pi d[/tex]
Therefore, perimeter of shape = [tex]\dfrac{\pi d}{2}+d[/tex]
b) Given:
- perimeter = 51.42 cm
- [tex]\pi[/tex] = 3.142
[tex]\implies 51.42 =\dfrac{3.142d}{2}+d[/tex]
[tex]\implies 51.42 =\dfrac{3.142d}{2}+\dfrac{2d}{2}[/tex]
[tex]\implies 51.42 =\dfrac{3.142d+2d}{2}[/tex]
[tex]\implies 51.42\times 2 =3.142d+2d[/tex]
[tex]\implies 102.84 =5.142d[/tex]
[tex]\implies d=\dfrac{102.84}{5.142}[/tex]
[tex]\implies d=20[/tex]
