The length of arc ab is 28.61 what is the circumference of the circle

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the calculus of the circumference depends on what is the value of central angle, so we can take for  example 120° the value of the central angle.

since the length of arc ab is 28.61, and the central angle is 120°, we can find the circumference simply by using the following formula:

ARC = Radius x Angle, so Radius = ARC / Angle = 28 .61  / 120° = 0.23 unit

the circumference of a circle is C = 2 x radius x Pie

C = 2 x radius x Pie = 2 x 0.23 x 3.14 = 1.49 unit

3x+9+4x+x=8x+9that's the answer for your question.