mac mini to early 2009 iMac for a display
I have an early 2009 iMac can i connect a new mac mini to sue iMac as the display?
No, not unless you got the model wrong.
Feb. 2016 https://discussions.apple.com/thread/7454088?answerId=29761388022#29761388022 - "Whether or not you can use your older iMac as a secondary display for your new iMac (known as Target Display Mode) will depend on the specific model. "
Use your iMac as a display with Target Display Mode - Apple Support - https://support.apple.com/HT204592