Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 1 - No. 23)

A boat sails 10 km due north and then 8 km in a south-easterly direction. To determine the final position of the boat you will need to consider:

Pythagoras' theorem

The sine rule

Trigonometry and vector addition

Only the sine rule

You'll need trigonometry (to deal with the angles) and vector addition (to combine the directions and distances).