Let's solve this circle arc length problem. We are given a circle with center O and a circumference of 36. We need to find the length of minor arc AC. Looking at the diagram, we can see that angle AOC appears to be a right angle, which is 90 degrees.To find the arc length, we use the arc length formula. The arc length equals the central angle divided by 360 degrees, multiplied by the circumference. This formula tells us that the arc length is proportional to the central angle. The larger the angle, the longer the arc.Now let's apply the formula to our problem. We know the circumference is 36, and the central angle is 90 degrees. Substituting these values into the formula, we get arc length equals 90 degrees divided by 360 degrees, times 36. This simplifies to one-fourth times 36, which equals 9.Therefore, the length of minor arc AC is 9. The correct answer is A. We can verify this makes sense because 90 degrees is one-quarter of 360 degrees, so the arc should be one-quarter of the circumference. One-quarter of 36 equals 9, which confirms our answer.欢迎使用数学解题助手。请您提供需要解答的具体题目，我将为您提供详细的解题步骤和说明。