Indoor air pollution has increased as improvements have been made in . A) heating and air-conditioning systems B) radon-resistant construction techniques C) energy conservation in the home D) green building construction E) all of these choices contribute to indoor air pollution

the only real purpose of sputnik 1 was to beat the us into space. we were getting close to launching a useful satellite, explorer 1 - which launched on january 31, 1958. the ussr had to beat that, so they launched sputnik 1 on october 4, 19

the answer is 12 as i may remember

: )

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y