Question

三角函数题化简

1、cos(a-π\2)\sin(a+5π\2) *sin(a-2π)*cos(2π-a)
2、sin(a+2\π)*cos(a-3π\2)*tan(π\2-a)

Answer 1

只会第一题/第二题不知道什么意思

Answer 2

1.cos(a-π/2)/sin(a+5π/2)*sin(a-2π)*cos(2π-a)
=cos(a-π/2)/sin(a+π/2)*sin(a)*cos(-a)
=-sin a/cos a*sin a*cos a
=-(sina)2

Answer 3

1、原式=cos(π/2-a)*sina*cos(-a)/sin(a+π/2)
=sina*sina*cosa/sin(π/2-a)
=sina*sina*cosa/cosa
=sin²a
2、原式=sin(π/2-a)*cos(π+π/2-a)/tana
=-cosacos(π/2-a)*cosa/sina
=-sinacosa*cosa/sina
=-cos²a