Finding the Focal Point If you decide to build a parabolic cooker, you will need to find the focal point of your cooker in order to place your water container where the sun's rays will be strongest. See It Online www.ies.co.jp/math/java/conics/focus/focus.html Determine It Yourself The formula for a parabola is f = x^{2}/4a. To find the focal point of a parabola, follow these steps: Step 1: Measure the longest diameter (width) of the parabola at its rim. Step 2: Divide the diameter by two to determine the radius (x) and square the result (x^{2}). Step 3: Measure the depth of the parabola (a) at its vertex and multiply it by 4 (4a). Step 4: Divide the answer from Step 2 by the answer to Step 3 (x^{2}/4a). The answer is the distance from the vertex of the parabola to its focal point. |