A kite 100 ft above the ground moves horizontally at a speed
of 8 ft/s. At what rate is the angle between the string and the
horizontal decreasing when 200 ft of string has been let out?

Question

A kite 100 ft above the ground moves horizontally at a speed
of 8 ft/s. At what rate is the angle between the string and the
horizontal decreasing when 200 ft of string has been let out?

anonymous · Answer

attachment

anonymous · Answer

i already solve it but its wrong....i can´t understand why

campbell_st · Answer

well it requires related rates...

dumbcow · Answer

you should use tan instead of cos because the diagonal is changing based on the angle

ranga · Answer

The 200 should not be substituted before taking the derivative.

anonymous · Answer

yes...i think both answerrs are right....i spenad like 3 hours trying to figured out the mistake....thanks a lot

dumbcow · Answer

tan(t) = 100/x

sec^2 t' = -100/x^2 * x'

t' = -100cos^2 x' / x^2

anonymous · Answer

yes i know how to s olve with tan....is just i want to know the mistake with cos instead of tan

anonymous · Answer

thanks bye

dumbcow · Answer

ok :)