# Find the length of arc AB, round to the nearest tenth.

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Find the length of arc AB, round to the nearest tenth.
 A. 6.5 B. 8.3 C. 13.1 D. 14.2

Find the radius of circle A, if the area of the shaded region is 47.5 cm2
 A. 7 cm B. 7.5 cm C. 8 cm D. 8.5 cm

How do you find the arc length of a central angle of a circle?
 A. B. C. D. none of the above

asked Sep 25, 2014

## 3 Answers

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Best answer

(1).

Calculate the length of the arc AB by using formula :

L = (C/360) * 2πr, where C = is the central angle of the arc in degrees, r = the radius of the arc.

Substitute C = 125, π = 22/7 ≅ 3.142 and r = 6 in the above formula.

AB = 125/360 * 2 * 22/7 * 6

= 33000/2520

≅ 13.1 units.

The option C is correct.

answered Sep 25, 2014
selected Sep 26, 2014 by tonymate
+1 vote

(2).

Calculate the radius of the circle by using the sector area formula :

A = (C/360) * πr2, where C = is the central angle of the arc in degrees, r = the radius of the arc.

Substitute A = 47.5 cm2, C = 85 and π = 22/7 ≅ 3.142 in the above formula.

47.5 = 85/360 * 22/7 * r2

64 r2

r = ± 8.

Radius of the circle cannot be expressed with negative sign.

r = 8 cm.

The option C is correct.

answered Sep 25, 2014
edited Sep 25, 2014 by bradely
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(3).

Calculate the length of the arc by using formula : s = r * θ, where θ = is measured in radians, r = the radius of the circle.

The option C is correct.

answered Sep 25, 2014