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- Homework Statement
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- Relevant Equations
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When I take ##x = 2\cos(t)## and ##y = 2\sin(t)##, the integral becomes ##\int_{t=\frac{\pi}{2}}^0 4(2\cos(t))^2 \cdot 2 dt = -8\pi##. The final answer is ##8\pi##. Why is my method wrong?

I played around with desmos and the parameterisation seems correct: https://www.desmos.com/calculator/fgid1zbbir (starting at ##\frac{\pi}{2}## and ending at ##0##.

Question/Answer source: https://tutorial.math.lamar.edu/Solutions/CalcIII/LineIntegralsPtI/Prob9.aspx