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10 grade maths

If the area and arc length of the sector of the circle is 60 cm² and 20 cm respectively, then the diameter of the circle is

  • a) 6 cm
  • b) 12 cm
  • c) 24 cm
  • d) 36 cm

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10 Months agoGrade
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1 Answer

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ApprovedApproved Tutor Answer10 Months ago

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).