1. "Old Pythagoras, eh? Three, four, five. And 20, 21, 29. The sides of two right-angled triangles," said Bob, looking down over the boy's shoulders. "Is that homework?" "Not really, Dad," Joe replied. "Those are the two smallest right-angled triangles with the middle side just one more than the shortest. I'm trying to find the next biggest one." What about it?

117, 119, 175

119, 120, 169

122, 126, 189