SOLUTION: Find standard. Form or parabola when directix is y=4 and focus is (6,-6)

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Question 426979: Find standard. Form or parabola when directix is y=4 and focus is (6,-6)
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

 Using The standard form is %28x+-h%29%5E2+=+4p%28y+-k%29, where the focus is (h,k + p) 

Find standard form of parabola when directix is y=4 and focus is (6,-6)

Note the vertex is 'halfway' (along the line of symmetry, x = 6) 

between the directrix: y = 4 and the focus (6,-6).(this parabola opens downward)

distance between directrix and focus: 4-(-6) = 10 , 10/2 = 5...  

p = -5... therefore, the Vertex Pt is (6,-1)

 (x-6)^2 = -20(y+1)  OR y = (-1/20)(x-6)^2 - 1