Question

The radius of a circle is 9 feet. What is the length of a 90° arc?

Answer 1

`(9\pi )/(2)` feet, or 14.14 feet

Explanation:

Use the arc length formula:

s = rθ

To use the formula, we have to convert the central angle to radians.

90° is equivalent to
`(\pi )/(2)` radians, so plug this and the radius into the formula:

s = rθ

s = (9)(
`(\pi )/(2)`)

s =
`(9\pi )/(2)`

So, the length of the arc is
`(9\pi )/(2)\\` feet, or approximately 14.14 feet