The base of a solid is the region between the curve yequals3 cosine x and the ​x-axis from xequals0 to x equals StartFraction pi Over 2 EndFraction . The cross sections perpendicular to the ​x-axis are squares with bases running from the ​x-axis to the curve. Find a formula for the area​ A(x) of the cross sections of the solid perpendicular to the​ x-axis.