What is the radius of a circle function, represented as x^2 + y^2 = r^2, if the x-coordinate and y-coordinate of a point on the circle are both equal to 5?
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Math question: Find the derivative of f(x) = sin^2(x)cos(2x) - tan(x) + ln(5x)^3.
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What is the probability of flipping exactly 3 heads in 5 fair coin flips?