设底宽为x,矩形高为y,a = S[半圆] + S[矩形]= (1/2)π((x/2))(^2)+xy所以 y = a/x - πx / 8铁丝长 f(x) = πx/2 + 2y + x = πx/2 + x + 2a/x - πx/4 = πx/4 + x + 2a/x当 f(x) 取极值时,f'(x)= 0 = π/4 + 1 - 2...