What are the characteristics of the circle function with equation x^2 + y^2 = r^2? Provide a detailed explanation including its center, radius, and properties related to symmetry, intercepts, and graph shape.
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What is the length of side a in a triangle, given angle A is 30 degrees, angle B is 50 degrees, and side b is 5 units?
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In a set of data, what is the formula for calculating the variance?