Answer: 0
Step-by-step explanation: To find the average value, take the definite integral of the function over the interval, then divide by the length of the interval. The indefinite integral of cos(18x) is sin(18x)/18 using u-substitution, and using the fundamental theorem of calculus, the definite integral of cos(18x) equates to 0. Of course, 0/(pi/2-0) also equals 0, so the answer is 0.