Answer with Step-by-step explanation:
We are given that
Radius of circular disk=r=21 cm
dr=0.2 cm
a.Area of circular disk=A=[tex]\pi r^2[/tex]
[tex]d A=2\pi rdr[/tex]
[tex]d A=2\pi (21)(0.2)=8.4 \pi cm^2[/tex]
[tex]d A=8.4\times 3.14 [/tex]
Where [tex]\pi=3.14[/tex]
[tex]d A=26.38 cm^2[/tex]
b.Relative error=[tex]\frac{dA}{A}=\frac{26.38}{\pi (21)^2}[/tex]
Relative error=[tex]0.0191[/tex]
Percentage(%) error=[tex]0.0191\times 100=1.91[/tex]%
