Class 10

Math

All topics

Some Applications of Trigonometry

An aeroplane leaving from Bismarck travels on a bearing of $120_{o}$, as shown in the figure. If the plane flew at an average rate of $400$ miles per hour, how many minutes (approx) had it been in the air when it was $295$ miles from Pierre?

- $51$
- $56$
- $29$
- $67$

We thus have $sin(60_{o})=x295 $ where $x$ is the distance flown by the plane.

That distance becomes $x=3 295×2 $

$x=340.63$ mi

Since the speed is $400$ miles per hour, the time becomes $340.63/400×60=51.0945$ minutes