What is the focal length of the parabola with equation shown below?

Patterns:  vertical : y = a(x - h)² + k          horizontal: x = a(y - k)² + h

Look at the patterns above and remember these key points.

1) if the x is squared, the parabola is vertical. It either opens up or down. 
    if the y is squared, the parabola is horizontal. It either opens left or right.

2) if a is positive, the parabola opens up or to the right.
    if a is negative, the parabola opens down or to the left

3) the vertex is at (h,k). Be very careful. locations of h and k varies if the parabola is vertical or horizontal. its sign is also different in those positions

The answer to this question is c

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