Two forces, F1 and F2, are represented by vectors with initial points that are at the origin. The first force has a magnitude of 20 lb and the terminal point of the vector is point P(1, 1, 0). The second force has a magnitude of 80 lb and the terminal point of its vector is point Q(0, 1, 1). Let F be the resultant force of forces F1 and F2.Find the direction angle of F.

answer: the correct answer for the fill in the blank is rods.

rods are the specialized photoreceptor cells that are present in the retina of human eye. they are responsible for vision in the night time ( also called scotopic vision). they have very low visual acuity and color distinguishing ability.

as they are responsible for vision in night time, therefore they are found predominantly in the nocturnal animals.