Equal sign with a triagle above it?

[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

[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.

[frankR]

Thanks.[a)]