Question
Calculate these complex numbers and express your results in rectangular form: (a) $\frac{15 \angle 45^{\circ}}{3-j 4}+j 2$(b) $\frac{8 \angle-20^{\circ}}{(2+j)(3-j 4)}+\frac{10}{-5+j 12}$(c) $10+\left(8 \angle 50^{\circ}\right)(5-j 12)$
Step 1
We can do this by calculating the magnitude and the angle. The magnitude is $\sqrt{3^2+(-4)^2}=5$ and the angle is $\arctan\left(\frac{-4}{3}\right)=-53.13^{\circ}$. So, $3-j4$ can be written as $5\angle-53.13^{\circ}$. Show more…
Show all steps
Your feedback will help us improve your experience
Mirza Aslam Beig and 101 other Physics 102 Electricity and Magnetism educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
Evaluate the following complex numbers and express your results in rectangular form: (a) $2+\frac{3+j 4}{5-j 8}$ (b) $4 \angle-10^{\circ}+\frac{1-j 2}{3 \angle 6^{\circ}}$ (c) $\frac{8 \angle 10^{\circ}+6 \angle-20^{\circ}}{9 \angle 80^{\circ}-4 \angle 50^{\circ}}$
Evaluate, in polar form $2 \angle 30^{\circ}+5 \angle-45^{\circ}-4 \angle 120^{\circ}$ Addition and subtraction in polar form is not possible directly. Each complex number has to be converted into Cartesian form first. $$ \begin{aligned} 2 \angle 30^{\circ} &=2\left(\cos 30^{\circ}+j \sin 30^{\circ}\right) \\ &=2 \cos 30^{\circ}+j 2 \sin 30^{\circ}=1.732+j 1.000 \\ 5 \angle-45^{\circ} &=5\left(\cos \left(-45^{\circ}\right)+j \sin \left(-45^{\circ}\right)\right) \\ &=5 \cos \left(-45^{\circ}\right)+j 5 \sin \left(-45^{\circ}\right) \\ &=3.536-j 3.536 \\ 4 \angle 120^{\circ} &=4\left(\cos 120^{\circ}+j \sin 120^{\circ}\right) \\ &=4 \cos 120^{\circ}+j 4 \sin 120^{\circ} \\ &=-2.000+j 3.464 \end{aligned} $$ Hence $2 \angle 30^{\circ}+5 \angle-45^{\circ}-4 \angle 120^{\circ}$ $$ \begin{aligned} =(1.732+j 1.000)+(3.536-&j 3.536) \\ -(-2.000+j 3.464) \end{aligned} $$ $=7.268-j 6.000$, which lies in the fourth quadrant $$ \left.=\sqrt{\left[(7.268)^{2}+(6.000)^{2}\right.}\right] \angle \tan ^{-1}\left(\frac{-6.000}{7.268}\right) $$ $$ =9.425 \angle-39.54^{\circ} $$
Represent each complex number graphically and give the rectangular form of each. $$5.00\left(\cos 54.0^{\circ}+j \sin 54.0^{\circ}\right)$$
Complex Numbers
Polar Form of a Complex Number
Transcript
18,000,000+
Students on Numerade
Trusted by students at 8,000+ universities
Watch the video solution with this free unlock.
EMAIL
PASSWORD