Final Answer:
The equation of the parabola that opens to the left, with a vertex at (2,7) and a focal diameter of 12 is: \((y - 7)^2 = -48(x - 2)\).
Step-by-step explanation:
A parabola opening to the left has its focus to the left of the vertex. The standard form of the equation for a parabola with a horizontal axis is \((y - k)^2 = 4p(x - h)\), where \((h, k)\) is the vertex and \(p\) is the distance between the vertex and the focus.
Given the vertex at (2,7) and a focal diameter of 12, the focal width is 12, meaning the distance from the vertex to the focus (or from the vertex to the directrix) is \(p = \frac{12}{2} = 6\).
Since the parabola opens to the left, the focus is 6 units to the left of the vertex. Therefore, the focus is at (-4, 7). Using the formula \(4p = \text{focal width}\), we find \(4p = 12\) and thus, \(p = 3\).
Substituting the vertex (2,7) and the value of \(p\) into the equation gives \((y - 7)^2 = -48(x - 2)\), where the negative sign before \(48\) indicates the parabola opens to the left.