Complex numbers in algebraic and polar form

9000038606

Level: 
B
Find the algebraic form of the following complex number. \[ \cos \frac{\pi } {4} + \mathrm{i}\sin \frac{\pi } {4} \]
\(\frac{\sqrt{2}} {2} + \mathrm{i}\frac{\sqrt{2}} {2} \)
\(\frac{\sqrt{2}} {2} -\mathrm{i}\frac{\sqrt{2}} {2} \)
\(\frac{\sqrt{3}} {2} + \mathrm{i}\frac{\sqrt{3}} {2} \)
\(\frac{\sqrt{3}} {2} -\mathrm{i}\frac{\sqrt{3}} {2} \)

9000037408

Level: 
B
Find the polar form of the following complex number \[z=\frac{1} {\cos \frac{2\pi } {3} +\mathrm{i}\sin \frac{2\pi } {3} }. \]
\(\cos \frac{4\pi } {3} + \mathrm{i}\sin \frac{4\pi } {3}\)
\(\cos \left (-\frac{4\pi } {3}\right ) + \mathrm{i}\sin \left (-\frac{4\pi } {3}\right )\)
\(\cos \frac{3} {2\pi } + \mathrm{i}\sin \frac{3} {2\pi }\)
\(\cos \frac{3} {2\pi } -\mathrm{i}\sin \frac{3} {2\pi }\)

9000037409

Level: 
B
Find the polar form of the complex number \[z=\frac{1} {\cos \frac{7\pi } {6} +\mathrm{i}\sin \frac{7\pi } {6} }. \]
\(\cos \frac{5\pi } {6} + \mathrm{i}\sin \frac{5\pi } {6}\)
\(\cos \left (-\frac{5\pi } {6}\right ) + \mathrm{i}\sin \left (-\frac{5\pi } {6}\right )\)
\(\cos \frac{\pi }{6} + \mathrm{i}\sin \frac{\pi }{6}\)
\(\cos \left (-\frac{\pi }{6}\right ) + \mathrm{i}\sin \left (-\frac{\pi }{6}\right )\)

9000038609

Level: 
B
Find the algebraic form of the following complex number. \[ 5\left (\cos \frac{3\pi } {4} + \mathrm{i}\sin \frac{3\pi } {4}\right ) \]
\(-\frac{5\sqrt{2}} {2} + \mathrm{i}\frac{5\sqrt{2}} {2} \)
\(\frac{5\sqrt{2}} {2} -\mathrm{i}\frac{5\sqrt{2}} {2} \)
\(\frac{5} {2} + \mathrm{i}\frac{5} {2}\)
\(\frac{5} {2} -\mathrm{i}\frac{5} {2}\)