Math Question: Find the derivative of f(x) = 3x^4 - 2x^3 + 5x^2 - 7x + 9.
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Find the area of a triangle with base 8 cm and height 12 cm.
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Math question: In a circle, if an angle at the center is twice the size of an angle at the circumference, and the angle at the circumference measures 60 degrees, what is the measure of the angle at the center?