Should "a" be used in the titular expression? I've found instances in which "a" used :
This book presents a practical introduction to signal analysis techniques that are commonly used in a broad range of engineering areas such as biomedical engineering, communications, geophysics, speech, etc.
and those without "a" :
KNN algorithm is used in broad range of classification problems such as: medical diagnosis, image processing, predicting of properties of amino acids sequences.
I think both are identical, however, could not prefer one over another.
Best Answer
Both are not identical; the second is incorrect. It would be correct if range was plural, ie.
Otherwise, an article, "a", is required.