化简【cos(a +2π ) * tan(a +π )】/sin (a -2π)的值为 很急,会的帮个忙,谢谢

化简【cos(a +2π ) * tan(a +π )】/sin (a -2π)的值为 很急,会的帮个忙,谢谢
化简【cos(a +2π ) * tan(a +π )】/sin (a -2π)的值为 很急,会的帮个忙,谢谢

化简【cos(a +2π ) * tan(a +π )】/sin (a -2π)的值为 很急,会的帮个忙,谢谢
【cos(a +2π ) * tan(a +π )】/sin (a -2π)
=cos(a)tan(a)/sin (a)
=cos(a)sin(a)/sin (a)cos(a)
=1