Euclid's Elements Book X, Lemma for Proposition 33: Right triangle, Altitude, and Rectangles. Level: High School, SAT Prep, College geometry.
Let ABC be a right-angled triangle having the angle A right, and let
the perpendicular AD be drawn:
The Elements: Books I-XIII (Barnes & Noble Library of Essential Reading)
In its broad sense, education refers to any act or experience that has a formative effect on the mind, character, or physical ability of an individual...In its technical sense education is the process by which society, through schools, colleges, universities, and other institutions, deliberately transmits its cultural heritage--its accumulated knowledge, values, and skills--from one generation to another. George F. Kneller, Introduction to the Philosophy of Education (New York: John Wiley and Sons, 1971.)