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