Achain fits tightly around two gears as shown. what is the radius of the smaller gear? round your answer to the nearest tenth. 1.6 in. 9.6 in. 12.0 in. 6.4 in.

See image attached

We could find the length of the radius of the small circle using pythagorean theorem. There is a right triangle formed from the picture above. Pythagorean theorem states the sum of the squares of the perpendicular sides on the right triangle is equal to the square of its hypotenuse.

(8 - r)² + 20² = 21²
(8 - r)² + 400 = 441
(8 - r)² = 441 - 400
(8 - r)² = 41
8 - r = √41
r = 8 - √41
r = 8 - 6.403
r = 1.597
to the nearest tenth
r ≈ 1.6
The radius of the small circle is approximately 1.6 in

The answer of the above question is