The circumference of a circle is 42pie cm. Find the diameter, the radius, and the length of an arc of 90 degrees.

A. 42 cm; 84cm; 5.3pie cm.
B. 21 cm; 42 cm; 5.3pie cm.
C. 42 cm; 21 cm; 10.5pie cm.
D. 84 cm; 21 cm; 135pie cm.

C

Step-by-step explanation:

circumference : 42 π  cm

the equation to solve for circumference is : 2 π r  or dπ

radius : 42π /2π  = 21 cm

diameter is r*2

diameter : 21*2 = 42 cm

to find the arc of 90 degrees, divide the circumference by 4

42/4 = 10.5π  cm

by process of elimination, C shows

diameter: 42 cm

radius: 21 cm

and arc of 90 degrees: 10.5 π  

therefore, C is the correct answer

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step-by-step explanation: