using the fact that pi=22/7, find as a fraction the circumference and area of a circle with diameter 4/5 cm

Question

using the fact that π= 22/7, find the circumference and area of a circle with a diameter of 4/5 cm.

Answer 1

C: circumference

A: area

r: radius

d: diameter

 

C=2πr

A=πr^2

d=2r

 

r=d/2

r=0.4

C=(2)(22/7)(0.4)=2.514 cm

A=(22/7)(0.4)^2=0.502 cm^2

Answer 2

pi is theratio of circumference of a circle to its diameter.

 

so x/.8=22/7      so 7x=22times .8

 

solving for x=88/35

 

area=22/7 times (2/5)^2

 

 

88/175