Question 1100416
Alan sets off from Campsite A on a bearing of 100 degrees at an average speed of 5.6 kilometres per hour.
 At the same time Bob sets off from campsite B on a bearing of 70 degrees.
 After 3 hours they both arrive at campsite C.
 Who has the faster average speed and by how much?  
:
let s = Bob's speed to C
then
3s = the dist from B to C
:
Draw this out to form a triangle A B C, where
A = 180-100 = 80 degrees
B = 70 degrees
C = 180 - 80 - 70 = 30 degrees
:
Alan's dist (AC): 3 * 5.6 = 16.8 km, (opposite angle B:
Use the law of sines
{{{(3s)/sin(80)}}} = {{{16.8/sin(70)}}}
I got
3s = {{{16.54/sin(70)}}}
3s = 17.606
s = 17.606/3
s = 5.87 km/hr, about .3 km/hr faster