# Homework Help: Vout = (a+jb)Vin, what do A and B stand for?

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1. Mar 21, 2015

### ConfusedBrendan

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

I was given a graph with two waves on it, the input and output wave. I found the frequency of the waves, change in magnitude and change in phase. The last question asks me to write the transformation from input to output as a phasor and he gave the relevant equation below.

Vout = output voltage, Vin = input voltage, j is i or the square root of -1, and I don't know what A and B stand for

2. Relevant equations

Vout = (a+jb)Vin

3. The attempt at a solution

I solved the change in amplitude = 0.7 and the change in phase is -13.3 degrees

2. Mar 21, 2015

### axmls

Do you know how to convert a magnitude and an angle to a complex number?

It would also help to see the graph.

3. Mar 23, 2015

### rude man

There is a widely known relation changing a + jb to ρ exp(jφ) where ρ is magnitude and φ is phase. Easy to derive too. Hint: Euler relation for exp(jφ).