To find the diameter of the circle given the area and arc length of the sector, we can use the following formulas:
Key Formulas
- Area of the sector: A = (θ/360) × πr²
- Arc length: L = (θ/360) × 2πr
Given Values
The area (A) is 60 cm² and the arc length (L) is 20 cm. We need to find the radius (r) first.
Finding the Angle θ
From the arc length formula, we can express θ in terms of r:
20 = (θ/360) × 2πr
Rearranging gives:
θ = (20 × 360) / (2πr) = (7200) / (2πr) = (3600) / (πr)
Substituting θ into the Area Formula
Now, substitute θ into the area formula:
60 = (θ/360) × πr²
Substituting for θ:
60 = ((3600)/(πr) / 360) × πr²
60 = (10r)
Thus, r = 6 cm.
Calculating the Diameter
The diameter (d) is twice the radius:
d = 2r = 2 × 6 = 12 cm.
Final Answer
The diameter of the circle is 12 cm, which corresponds to option b).