Question

作出下列各角的正弦值余弦值正切值

1. π /3
2. 5π/6
3. -2π/3
4. -13π/6

Answer 1

sinπ/3=√2/2
cosπ3=1/2
sin5π/6=1/2
cos5π/6=-√3/2
sin-2π/3=-√2/2
cos-2π/3=1/2
sin-13π/6=-1/2
cos-13π/6=√3/2

√是根号
另附：
诱导公式
sin(-α) = -sinα cos(-α) = cosα tan (-α)=-tanα sin(π/2-α) = cosα cos(π/2-α) = sinα sin(π/2+α) = cosα cos(π/2+α) = -sinα sin(π-α) = sinα cos(π-α) = -cosα sin(π+α) = -sinα cos(π+α) = -cosα tanA= sinA/cosA tan（π/2＋α）＝－cotα tan（π/2－α）＝cotα tan（π－α）＝－tanα tan（π＋α）＝tanα 诱导公式记背诀窍：奇变偶不变，符号看象限

Answer 2

π/3=#/180°，#=60°然后算正余弦正切