>>296 >>300

y = √{(1/2)^2 + (4/3 - 2x)^2}   (←等積条件)

x + 2y ≧ (8+3√15)/12 = 1.6349

x = 2/3 - 1/(4√15) = 2/3 - (tanδ)/4 = 0.60212

sinδ = 1/4,