A street light is at the top of a "20" ft tall pole. a woman "6" ft tall walks away from the pole with a speed of "5" ft/sec along a straight path. how fast is the tip of her shadow moving when she is "50" ft from the base of the pole?
Height of Woman, w = 6 ft. Distance Between Woman and Pole, s = 35 ft. Speed of Woman, ds/dt = 5 ft./sec Length of Shadow = L Distanc Between Woman and End of Shadow = x p / (s + x) = w / x 13 / (35 + x) = 6 / x 13x = 6(35 + x) 13x = 210 + 6x 13x - 6x = 210 7x = 210 x = 210 / 7 x = 30
L = s + x L = 35 + 30 L = 65
p / L = w / (L - s) 13 / L = 6 / (L - s) 13(L - s) = 6L 13L - 13s = 6L 13L - 6L = 13s 7L = 13s
