The problem states that the radius of the circle is 9 cm. We denote the radius by r.

The formula for the circumference of a circle is C = 2π r. Substituting the given radius r = 9 cm into the formula, we get C = 2 × π × 9 = 18π cm.

The formula for the area of a circle is A = π r². Substituting the radius r = 9 cm into the formula, we get A = π × (9)² = 81π cm².

A circle has radius 9 cm. Find its circumference and area. (ref ushj9)

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Step-by-Step Solution

Step 1: Identify Given Information

The problem states that the radius of the circle is $9 \text{ cm}$ . We denote the radius by $r$ .

Step 2: Calculate Circumference

The formula for the circumference of a circle is $C = 2\pi r$ . Substituting the given radius $r = 9 \text{ cm}$ into the formula, we get $C = 2 \times \pi \times 9 = 18\pi \text{ cm}$ .

Step 3: Calculate Area

The formula for the area of a circle is $A = \pi r^2$ . Substituting the radius $r = 9 \text{ cm}$ into the formula, we get $A = \pi \times (9)^2 = 81\pi \text{ cm}^2$ .