The parabola equation is and the point is .

Since the square term is , the parabola is vertical.

Standard form of the vertical parabola is ,

where is vertex.

Focus .

The parabola equation .

Compare the above equation with .

Since  is negative, the parabola opens down.

Vertex .

Focus .

Graph:

Graph the , focus and the point .

observe the graph:

The distance between focus and the point of tangency is .

is the one leg of the isosceles triangle.

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Substitute and .

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Find the point , the end point of the other leg of the isosceles triangle.

Since  is positive the parabola opens down and will be to the above the focus.

.

The tangent line passes through the points and .

The slope of tangent line is .

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The point-slope form of line equation is .

Substitute and .

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The tangent line equation is .

The tangent line equation is .