若sin（x+5π/12）的平方-sin(x-5π/12的平方）=-根号3/4 且x∈（3π/4,π）,求tanx
问题描述：
若sin（x+5π/12）的平方-sin(x-5π/12的平方）=-根号3/4 且x∈（3π/4,π）,求tanx
答
sin^2(x+5π/12) - sin^2(x-5π/12) =- √3/4{ sin(x+5π/12) + sin(x-5π/12) } { sin(x+5π/12) - sin(x-5π/12) } =- √3/42sin[(x+5π/12+x-5π/12)/2] cos[(x+5π/12-x+5π/12)/2] * 2cos[(x+5π/12+x-5π/12)/...