SOLUTION: a parabola has its vertex at the origin, and the equation of its directrix is y=-10. Find the cordinates of the focus. A. (0,-10) B. (-10,0) C. (0,10) D. (10,0)

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: a parabola has its vertex at the origin, and the equation of its directrix is y=-10. Find the cordinates of the focus. A. (0,-10) B. (-10,0) C. (0,10) D. (10,0)      Log On


   

Question 965257: a parabola has its vertex at the origin, and the equation of its directrix is y=-10. Find the cordinates of the focus.
A. (0,-10)
B. (-10,0)
C. (0,10)
D. (10,0)
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
vertex at the origin (h,k)=(0,0)
directrix: y=k-p=-10=> since k=0 we have 0-p=-10=>p=10
and, since focus is at (h,k%2Bp), we have (0,0%2B10)=> (0,10)
so, your answer is C. (0,10)