Chapter 2 - Differentiation - 2.6 Exercises - Page 153: 7

a) 12 ft/sec b) 6 ft/sec c) 3 ft/sec

y = tanx $\frac{dy}{dt} = sec^2(x) \frac{dx}{dt} $ dx/dt = 3 ft/sec a) x = -$\frac{\pi}{3} $ $\frac{dy}{dt} = sec^2(-\frac{\pi}{3} )(3) = 12$ b) x = -$\frac{\pi}{4} $ $\frac{dy}{dt} = sec^2(-\frac{\pi}{4} )(3) = 6$ c) x = 0 $\frac{dy}{dt} = sec^2(0 )(3) = 3$