# Homework Help: Geometric interpetation of a complex number in R^2

1. Sep 5, 2006

### Valhalla

For this problem i am given two complex numbers $$Z_1 , Z_2$$ and then a third which is the sum of the first two complex numbers $$Z_3$$. I am then asked to find the geometric interpetation of these numbers in $$\mathbb{R}^2$$. I am fine when graphing them in the complex plane but unsure of what they look like in $$\mathbb{R}^2$$. Do I just take the real part and graph a point in the $$\mathbb{R}^2$$? If so how do I determine which axis it would be on? Do you think this might be a typo?

2. Sep 5, 2006

### HallsofIvy

The standard "complex plane" is to plot the complex number a+ bi as the point (a, b). That is, the x-axis is the "real axis" and the y-axis is the "imaginary axis". It might occur to you that the sum of complex numbers, (a+ bi)+ (c+ di)= (a+c)+ (b+d)i looks a lot like (a+c, b+d), the sum of vectors. And that might lead you to think about a parallelogram.

3. Sep 5, 2006

### Valhalla

Yes, I understand that the complex numbers add like vectors. However, what I am confused about is that I thought that to graph them they needed to be in the complex plane. Like you said the x-axis is the real and the y-axis is the imaginary. When I look at the complex number (a+bi) and consider where that would be on R^2, I get confused.

So if I get what your saying then the complex number (a+bi) would just be the vector (a,b) in R^2? Am I overthinking this?

4. Sep 5, 2006

### HallsofIvy

Yes, that's exactly what I am saying!

5. Sep 5, 2006

### Valhalla

Ok I think I got it then. Thanks HallsofIvy!