Questions
Question 1
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Write \(e^{x+iy}\) in terms of real functions of \(x\) and \(y\).
Question 2
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What is \(|e^{x+iy}|\)?
Question 3
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Find \(e^{i\pi}\).
Question 4
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Find \(|e^{3+2i}|\).
Question 5
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Find the real and imaginary parts of \(e^{1+i\pi/2}\).
Question 6
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Evaluate \(\cos(iu)\) using the exponential definition.
Question 7
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Evaluate \(\sin(iu)\) using the exponential definition.
Question 8
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Show that \(e^{z+2\pi i}=e^z\).
Question 9
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Find \(e^{(1+i)(2-i)}\) in the form \(e^x(\cos y+i\sin y)\).
Question 10
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Find \(\operatorname{Re}(e^{2+i\pi})\) and \(\operatorname{Im}(e^{2+i\pi})\).
Question 11
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Explain why \(e^z\) never equals \(0\).
Question 12
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Verify the identity \(\cosh(iz)=\cos z\).
Question 13
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Find all \(z=x+iy\) such that \(|e^z|=e^4\).
Question 14
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Find all \(z=x+iy\) such that \(e^z\) is a positive real number.
Question 15
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For which real \(y\) is \(e^{2+iy}\) purely imaginary?
Question 16
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Find all real \(x,y\) such that \(e^{x+iy}=e^2\).
Question 17
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Show that \(\sinh(iz)=i\sin z\).
Question 18
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A learner claims \(\arg(e^{x+iy})=y\) exactly. Diagnose the statement.
Question 19
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Prove that \(e^z\) is periodic in the imaginary direction with period \(2\pi i\), but not with real period \(2\pi\).
Question 20
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Derive \(\cos^2 z+\sin^2 z=1\) from the exponential definitions.