The height of a submerged probe, hhh metres, relative to a fixed monitoring station at time ttt seconds is modeled by the equation
h(t)=2cos3t−3t+4,t>0 h(t) = 2 \cos 3t - 3t + 4, \quad t > 0 h(t)=2cos3t−3t+4,t>0where the argument of the cosine function is in radians. The probe first reaches a height of zero at time t=αt = \alphat=α, denoted by point PPP in its path.
Show that α\alphaα lies between 0.8 and 0.9.
The Newton-Raphson method can be used to find an approximate value for α\alphaα. The iteration formula for this method is given by
tn+1=tn+2cos3tn−3tn+46sin3tn+3 t_{n+1} = t_n + \frac{2 \cos 3t_n - 3t_n + 4}{6 \sin 3t_n + 3} tn+1=tn+6sin3tn+32cos3tn−3tn+4Using this iteration formula with t1=0.8t_1 = 0.8t1=0.8, find, to 4 decimal places, the value of: (i) t2t_2t2 (ii) t5t_5t5
The points QQQ and RRR are the first and second local minimum points on the probe's depth-time curve respectively for t>0t > 0t>0.
Using calculus, find the exact value of the ttt-coordinate of QQQ and the exact value of the ttt-coordinate of RRR.