Question

Determine the area of ​​the annulus if: R = 4cm; r = 2cm.

Answer 1

Answer:

Annulus

Solve for area

A≈37.7cm²

R Outer radius

4

cm

r Inner radius

2

cm

Solution

A=π(R2﹣r2)=π·(42﹣22)≈37.69911cm²

Answer 2

Answer:

37.6991 cm^2

Step-by-step explanation:

The dimensions of an annulus are defined by the two radii R, r, which are the radii of the outer ring and the inner ‘hole’ respectively. The area of a circular ring can be found by subtraction the area of a small circle from that of the large circle.

Here are formulas to find Area of Annulus.

A=π(R^2−r^2)

R=√ (r^2+A/π)

r =√(R^2−A/π)

Where,

A = Area of Annulus

R = Outer radius

r = Inner radius

(Pi) π = is approximately 3.1416

now, A=π(R^2−r^2) = Area of Annulus

or, A = π(4^2−2^2)

or, A = π(16−4)

or, A = π X 12

or, A = 37.6991 cm^2