How to use the word dumb in a sentence?

" This guy is so Dumb , he didn't know how to solve this Dumb Question " is a colloquial usage.

'She was born without functioning vocal cords, and so was dumb from birth until the throat surgery.' This is a correct usage of dumb, meaning unable to speak.

'An angel appeared, and the prophet was struck dumb' is also a correct usage, meaning temporarily unable to speak.