化簡：tan(π-α)tan(2π-α)cos(5π-α)/cos(3π/2+α) = -tanα
解根號方程：6x+√x-1=0
x=1/3（舍去負根）
所以：sinα = 1/3
因α沒有限制,所以α可能銳角可能鈍角
若α銳角
tanα = √2/4
tan(π-α)tan(2π-α)cos(5π-α)/cos(3π/2+α) = -√2/4
若α鈍角
tanα = -√2/4
tan(π-α)tan(2π-α)cos(5π-α)/cos(3π/2+α) = √2/4