Hey guys

A lighthouse is 10 km north-east of a ship travelling due west at 16 km/h.

i) How far is the ship from the lighthouse 45 min later?

ii) What is the bearing of the light-house from the ship at this time?

For i):

I used the cosine side formula…

$\displaystyle

LB^2 = 10^2 + 12^2 - 2(10)(12)cos45$

$\displaystyle LB = 8.6 cm

$

Which is wrong because the answers say it’s 20.3 km.

For ii):

I used the cosine angle formula:

cos $\displaystyle \angle $B = 55 degrees

Bearing = 270 + 55

=325 degrees T

Which is also wrong according to answer (070 degrees T)

Could someone please please show me how to do this question?