Question

The circumference of a circle is 78π cm. Find the diameter, the radius, and the length of an arc of 140°.

A. 156 cm; 39 cm; 160π cm
B. 39 cm; 78 cm; 15.2π cm
C. 78 cm; 156 cm; 15.2π cm
D. 78 cm; 39 cm; 30.3π cm

Answer 1

The correct answer is the option D, which is: D. 78 cm; 39 cm; 30.3π cm
The explanation is shown above:
1-The formula for calculate the circumference of a circle is:
C=2πr
78π=2πr
2- The radius is:
r=78π/2π
r=39 cm
3- The diameter is:
D=39 cm x 2
D=78 cm
4- The arc length is:
arc length=(140°π/180°)(39 cm)
arc length=30.3π cm