Is there enough info given in question

A ship which leaves a port, p, and travels south west, with constant speed, observes the flash of a lighthouse, l, ina direction S60W. After travelling for 10km, to a point,t, the ship observes the flash of the same lighthouse, due west.

Q1)Calculate how far the ship is from the lighthouse at this time i.e calculate length tl.

The answer given for this is 5.18km- Having sketched the diagram, I can't see that enough details have been supplied to use sine rule or otherwise to calculate this.

Q2) Calculate how close to the lighthouse the ship will pass.

The answer given here is 3.66km. Once again I cant figure this out. I took the point at which the ship passes the lighthouse to be the point at which t moves under the point l and sketched the resultant triangle. I used the answer from the first part to solve the triangle but had no joy.

Any ideas??

Where are you getting the 15 degree angle from? Thanks, by the way!

Quote:

Originally Posted by

**tom@ballooncalculus**

How do you get the 15 degree angle? Can work it out from there. Thanks for the help.