Misc: how many degrees are there in the three angles of a triangle?

Questions

What is the computer acronym for 'picture element'?

Who earned the nickname 'top gun' in the Persian Gulf War?

'Discipline without freedom is tyranny; freedom without discipline is chaos.'?

'The greater part of our happiness or misery depends on our disposition and not our circumstances.'?

'The greater the difficulty, the more the glory in surmounting it.'?