The amount of energy collected by a solar Wanel depends on the intensity of the sun's rays and the area cof the panel. Let the vector I represent the intensity, in watts per square centimeter, having the direction of the sun's rays Let the vector $\mathbf{A}$ represent the area, in square centimeters. whose direction is the orientation of a solar panel. See the figure. The total number of watts collected by the panel is given by $W=|\mathbf{I} \cdot \mathbf{A}|$
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