Explanation

Let the outer and inner radii be R and r. The chord of length 14 is tangent to the inner circle, so the distance from the centre to the chord is r, and half the chord (7) with r and R form a right triangle: R² = r² + 7², i.e. R² − r² = 49. The annulus area is π(R² − r²) = 49π = 49 × 22/7 = 154 cm². The answer is (D).