SOLUTION: find the trigonometric functions of alpha where the vertex of the parabola, y=X^2+8x-5, lies on its terminal side

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Question 422756: find the trigonometric functions of alpha where the vertex of the parabola, y=X^2+8x-5, lies on its terminal side
Answer by Gogonati(855) About Me  (Show Source):
You can put this solution on YOUR website!
Parabola with equation +y=X%5E2%2B8x-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