Maths
posted by Sam .
A rock, R, is 40 km from a harbour, H, on a bearing of 040°. A port, P, is 30 km from R on a
bearing of 130°.
Draw a sketch showing the points H, R and P and work out the size of angle HRP.

I hope you made the sketch.
I have a nice rightangled triangle HRP
with angle R = 90° , HR = 40, RP = 30 
Thanks.
Could you tell me the angles for H and P
R= 90
H= ?
p = ? 
use simple trig
for angle H
tanH = opposite/adjacent
= 30/40 = .75
angle H = appr.36.9°
then by simple subraction, angle P = 9036.9 = 53.1°
use 2nd Tan on your calculator
(tan inverse or arctan, depending on your calculator
on mine I do:
2ndF
tan
.75
=
to get 36.869... 
Thanks.

Can you tell me the bearing of P from H?