Chapter 6: Problem 40
Explain why there does not exist a number \(t\) such that the vectors \((2, t)\) and \((3, t)\) are perpendicular.
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Chapter 6: Problem 40
Explain why there does not exist a number \(t\) such that the vectors \((2, t)\) and \((3, t)\) are perpendicular.
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Suppose \(\mathbf{u}\) and \(\mathbf{v}\) are vectors. Show that $$ |\mathbf{u} \cdot \mathbf{v}| \leq|\mathbf{u}||\mathbf{v}| $$ [This result is called the Cauchy-Schwarz Inequality. Although this problem asks for a proof only in the setting of vectors in the plane, a similar inequality is true in many other settings and has important uses throughout mathematics.]
Show that if \(z\) is a complex number, then the imaginary part of \(z\) is in the interval \([-|z|,|z|]\).
Write each expression in the form \(a+b i,\) where \(a\) and \(b\) are real numbers. $$ \left(\frac{1}{2}-\frac{\sqrt{3}}{2} i\right)^{3} $$
Show that if \(\mathbf{u}\) and \(\mathbf{v}\) are vectors, then $$ |\mathbf{u}+\mathbf{v}|^{2}=|\mathbf{u}|^{2}+2 \mathbf{u} \cdot \mathbf{v}+|\mathbf{v}|^{2} $$.
Write $$ \left(\cos \frac{\pi}{7}+i \sin \frac{\pi}{7}\right)\left(\cos \frac{\pi}{9}+i \sin \frac{\pi}{9}\right) $$ in polar form.
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