Parabola Help

How do I find the focus just from looking at a graph?
In the link below I have a screenshot of a parabola. I think the Focus is (4,0)
http://gyazo.com/ed37c6ae63a875a4d4a05b6fbc6d9591

In addition to that, in the following graph, is the directrix of parabola? I think it is x = -5
http://gyazo.com/7377f7108554c08443c93d78957df350

Question

Parabola Help

How do I find the focus just from looking at a graph?
In the link below I have a screenshot of a parabola. I think the Focus is (4,0)
http://gyazo.com/ed37c6ae63a875a4d4a05b6fbc6d9591

In addition to that, in the following graph, is the directrix of parabola? I think it is x = -5
http://gyazo.com/7377f7108554c08443c93d78957df350

ganeshie8 · Answer

By definition of parabola, the distances from any-point-on-the-parabola to the directrix and focus are equal : 

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