# Equal sign with a triagle above it?

1. Mar 12, 2004

### frankR

In my EM text book it uses a equal sign with a triangle on top to define the intrinsic impedence of a lossless medium.

I think it means definition but I'm not certain.

The text is 2004 edition of author Ulaby titled Fundametals of Applied Electromagnetics, pg. 265.

Thanks

2. Mar 12, 2004

### jamesrc

You're right. This symbol: $$\triangleq$$ means that it is equal to by definition.

I've also seen the three lined equal sign, $$\equiv$$, used in definition statements.

3. Mar 13, 2004

Thanks.