Instructions to calculate a reflectors focal point for a parabola…
1. Square the dish's diameter. With this example, imagine a dish with a diameter of 3 feet: 3^2 = 9.
2. Divide the result by the depth of the dish. If the dish has a depth, for instance, of 1.2 feet: 9 / 1.2 = 7.5.
3. Divide this result by 16: 7.5 / 16 = 0.46875 feet, or approximately 5.6 inches. This is the dish's focal length.
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