1. **State the problem:** We need to find the radius $r$ of a circular aquarium tank. 2. **Analyze the given information:** The diameter is divided into two radii $r$ and $r$, so the diameter is $2r$. 3. **Use the right triangle formed:** The triangle has hypotenuse 35 ft and one leg 14 ft. The other leg is the radius $r$ minus 14 ft (since the leg from E to C is 14 ft, and the radius extends from center to edge). 4. **Apply the Pythagorean theorem:** $$35^2 = 14^2 + r^2$$ 5. **Calculate:** $$1225 = 196 + r^2$$ 6. **Isolate $r^2$:** $$r^2 = 1225 - 196$$ $$r^2 = 1029$$ 7. **Find $r$ by taking the square root:** $$r = \sqrt{1029} \approx 32.08$$ 8. **Final answer:** The radius of the aquarium tank is approximately 32.08 feet.