Question

求满足下列方程的x的集合,1.sinx= - 根号3 /22.cos(2x- π/6）=1/2

Answer 1

用单位圆法很好解

1 当x=-60°（-π/3) 或者x =-120°(-2π/3）时为单位圆内所求 那么与这两个角终边相同的角就是他的解集

{x=2kπ-π/3 或x=2kπ-2π/3 k∈Z}

2.cos(2x-π/6)=1/2

2x-π/6 =2kπ+π/3 或者 2x-π/6 =2kπ+2π/3

2x =2kπ+π/2 2x=2kπ+5π/6

x=k派+π/4 或 x= kπ+5派12 k∈Z