Reply #2: Leadership is an art...

[Orsino]

...and anger has its uses--ask any marine drill instructor. Acting angry can be motivational when it comes to simple tasks, expecially when the leader maintains a veneer of professionalism. Someone who has his act together while--apparently or actually--angry dons a mantle of righteousness that can be mightily inspiring.

The trick, then, which I have by no means mastered, is not to let your displeasure interfere with your judgement. You can use it as an attention-getting tool, or even to throw another person off his game.