已知cos(x-π/6)=-根号三分之三 则cos(x)+cos(x-π/3)的值是
问题描述:
已知cos(x-π/6)=-根号三分之三 则cos(x)+cos(x-π/3)的值是
答
∵ cos(x- π / 6)= - √3 / 3∴ cos x + cos(x - π / 3)= cos x + cos x cos π / 3 + sin x sin π / 3= cos x + (1 / 2)cos x + (√3 / 2)sin x= (3 / 2)cos x + (√3 / 2)sin x= √3 【 (√3 / 2...