00:01
We're asked to prove a statement about the complex numbers.
00:05
The statement is that for any complex numbers, z and w, the modulus of z plus w is less than or equal to the modulus of z plus the modulus of w.
00:15
This is sometimes referred to as the triangle inequality for complex numbers.
00:23
To prove this statement, we're going to have to write z and w, which are complex numbers as a plus bi, and c plus d -i for some a, b, c, and d in the real numbers.
00:47
And let's consider the vectors, u with components a -b, and v with components c -d.
00:58
These are vectors in r2.
01:04
Well, notice that the modulus of our complex number is z.
01:09
This is the square root of a squared plus b squared.
01:13
This is actually the same as the magnitude of v.
01:16
And likewise, the modulus of w is equal to the magnitude, i'm sorry, the magnitude of u, and the modulus of w is the magnitude of v.
01:25
Got those backwards...