Use a graphing utility to represent the complex number in standard form.Round your answer to 4 decimal places. $5 \left( \cos \frac { \pi } { 3 } + i \sin \frac { \pi } { 3 } \right)$
A)4.3301 + 2.5i
B)2.5 + 4.3301i
C)2.5 - 4.3301i
D)4.3301 - 2.5i
E)None of the above

Question

Use a graphing utility to represent the complex number in standard form.Round your answer to 4 decimal places.   $5 \left( \cos \frac { \pi } { 3 } + i \sin \frac { \pi } { 3 } \right)$  
A)4.3301 + 2.5i
B)2.5 + 4.3301i
C)2.5 - 4.3301i
D)4.3301 - 2.5i
E)None of the above

Quizplus · Accepted Answer

The complex number is in polar form $r(\cos \theta + i\sin \theta)$, where $r = 5$, $\theta = \frac{\pi}{3}$. Converting to standard form $a + bi$, we calculate $a = r\cos\theta = 5\cos\frac{\pi}{3} = 2.5$ and $b = r\sin\theta = 5\sin\frac{\pi}{3} = 4.3301$. Therefore, the standard form is $2.5 + 4.3301i$.

Use a Graphing Utility to Represent the Complex Number in Standard