lcd broken and unplugged, need to reinstall OS with external monitor

ok .. let's make this short and sweet

imac 21"5 mid 2010 .. LCD dead, original HDD failure.

new HDD installed, need to re install OS tru EXTERNAL MONITOR

since the LCD is unplugged from logic board, if i have the right cable for outside monitor ..

will the imac automatically goes to external monitor ?

thanks !!