cosinus 30,cosinus 40

[tex] \frac{x}{180} = \frac{y}{ \pi } [/tex]
y=30×π/180=π/6
alors:
cos(30)=cos(π/6)=√3/2

y=40×π/180=2π/9
alors:
cos(40)=cos(2π/9)=0.766044