Two vessels left the same port at same time. One took the route N 42 degrees E at the rate of 15km/hr. The second travelled in the direction S 18 degrees E at a certain uniform rate. Two hours after leaving the port they were found to be 70km apart. At what rate did the second ship travel?
2026-05-05 13:47:22.1777988842
Should I use law of cosines or Law of sines? Confusing
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The second ship's speed is in km/h is the value $v$ for which a length-$15$ vector N $42^\circ$ E, plus a length-$v$ vector N $18^\circ$ W (I'll leave it to you to compute the angle $\theta$ between these), has length $35$. You need the cosine law, viz. $1225=15+v^2-30v\cos\theta$, a soluble quadratic in $v$.