You are Here: Home >< Maths

# M1 Bearing Watch

1. Hi
im doing http://www.mei.org.uk/files/papers/2011_june_m1.pdf
anyway im stuck on question 6 ii. The direction of motion is 4i+5j
Ive made a right angle triangle with one side 4 (in the x direction) and one side 5 (in the y direction)

i cant figure out which angle i should be working out (arctan5/4 or arctan4/5) and why. i dont know how to get the bearing from this too
any help

thanks
2. (Original post by starwarsjedi123)
Hi
im doing http://www.mei.org.uk/files/papers/2011_june_m1.pdf
anyway im stuck on question 6 ii. The direction of motion is 4i+5j
Acceleration is -2j.

So velocity at t=2.5 is 4i-5j

Ive made a right angle triangle with one side 4 (in the x direction) and one side 5 (in the y direction)

i cant figure out which angle i should be working out (arctan5/4 or arctan4/5) and why. i dont know how to get the bearing from this too
any help

thanks
See attached.

A bearing is a clockewise angle from due North - the angle in green.

You can work out either angle a, or angle b.

Bearing is 90+a, or 180-b

where a is arctan5/4 and b is arctan4/5

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: May 24, 2016
Today on TSR

### What is the latest you've left an assignment

And actually passed?

### Simply having a wonderful Christmas time...

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

## Make your revision easier

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

Can you help? Study help unanswered threads

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.