In mathematical induction, showing that something works for the first case, or that P1 is true. angle of depression. The angle formed by a horizontal line and an observer's line of sight to an object below. angle of elevation. The angle formed by a horizontal line and an observer's line of sight to an object above.
Plankton's voice is provided by American actor Mr. Lawrence. The voice Lawrence uses for Plankton originated as an imitation of one of his deep-voiced friends from high school. On television, he first used the voice for incidental characters on Rocko's Modern Life.
Mr. Lawrence is a writer on SpongeBob SquarePants who also does the voices of Plankton and Larry the Lobster (I once saw an interview when he said he puffs out his chest while he's recording to get the right sound for Larry). Mr. Lawrence is not necessarily a career voice actor but takes roles in cartoons he's writing.