Question 422756
Parabola with equation {{{ y=X^2+8x-5}}} has for vertex the point (-4,-21).
This point lies on the third quadrant and the slope of the line that pases on
(-4,-21) and (0,0) is: m= (0+21)/(0+4)=21/4. As we know the slope of the line is equal to the tangent of the angel that the line form with x-axis.

    Tan(a)=21/4

   (a)= arctan (21/4)     ( (a) is the measure of the angle)

     (a)= 80 degree.

Since the vertex of parabola is in the third quadrant the angel is 180+80=260 degree.
          Tan(260)=5.67, Sin(260)=-0.98  and Cos(260) =-0.17