The right triangle has one 90 degree angle and two acute (< 90 degree) angles. Since the sum of the angles of a triangle is always 180 degrees... y + z = 90 degrees. The two sides of the triangle that are by the right angle are called the legs... and the side opposite of the right angle is called the hypotenuse.
They were called the Hollywood 10 and accused of being communist. I don't think you would find many people who can name them all.
McCarthyism was a campaign against so called communists in the US government and other institutions carried out under Senator Joseph McCarthy in the period 1950-54. Many of the accused were blacklisted or lost their jobs, although most did not in fact belong to the Communist Party. It was similar to what we now call witch hunts.