# Rect. and Polar with complex numbers (1 Viewer)

### Users Who Are Viewing This Thread (Users: 0, Guests: 1)

#### krnhseya

1. The problem statement, all variables and given/known data

B= 4-j2. Find $$\sqrt{B}$$ in rectangular and polar notation.

2. Relevant equations

n/a

3. The attempt at a solution

i can figure out that in rectangular form by using the calculator and converting those back into polar form but how can i do this without calculator?

#### chroot

Staff Emeritus
Gold Member
When you multiply two complex numbers together, their magnitudes are multiplied and their angles are added.

- Warren

#### krnhseya

magnitude of B = sqrt(4^2 + (-2)^2)
and use tangent to find the angle.

but i am asked to find square root.

#### chroot

Staff Emeritus
Gold Member
You're looking for a complex number, the square root of B. You know that if you multiply the square root of B by itself, you get B. Find the complex number that, when multiplied by itself (using the "rule" I have already given you), results in B.

- Warren

...?

#### krnhseya

sorry but last 2 posts dont help me at all;
it's quite obvious that sqrt(b) ^2 = b...and i know how to find magnitude and angle once i get it in forms of X + yj

### The Physics Forums Way

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving