Which pairs (if any) of these vectors are: a) Are perpendicular?
(b) Are parallel?
(c) Have an angles less than π/2 between them?
(d) Have an angle of more than π/2 between them?

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters

Anew test for ra is being developed. the test is administered to 750 patients with ra and 750 without ra. for the sake of the question, assume the prevalence of ra in this population is 50%. of the 750 patients with ra, 575 have a positive result. of the 750 patients without ra, 150 have a positive result. what is the positive predictive value of the new test? a575/(575+150) b. 600/(600+ 150) c. 575/(575+125) d. 600/(600+ 125)

40 points which is the equation of a line perpendicular to the line with the equation: y = 1/4x + 2 a : y = -4x - 7 b : y = 4x + 2 c : y = 1/4x - 1/2 d : y = -1/4x + 3