Robots with telescoping arms are sometimes used to perform tasks (e. g., welding or placing screws) where access may be difficult for other robotic types. during a test run, a robot arm is programmed to extend according to the relationship r = 3 + 0.5 cos(4θ) and the arm rotates according to the relationship θ = −(π/4)t 2 + πt where r is in feet, θ is in radians, and t is in seconds. determine the velocity and acceleration of the robot tip a at t = 3 s