(cosπ/8+sinπ/8)（cos^3π/8-sin^3π/8）=(cosπ/8+sinπ/8)（cosπ/8-sinπ/8）（cos^2π/8+cosπ/8*sinπ/8+sin^2π/8）=（cos^2π/8-sin^2π/8）(1+0.5sinπ/4)=cosπ/4(1+0.5sinπ/4)=根下2/2(1+根下2/4)=根下...