You are Here: Home >< Maths

# Vectors question watch

1. Given that a=pi+qj and has magnitude 10 and makes an angle theta with the positive x-axis where sin theta = 3/5. Find the possible values of p and q.

Why is p allowed to be negative yet q isn't??
2. (Original post by dont know it)
Given that a=pi+qj and has magnitude 10 and makes an angle theta with the positive x-axis where sin theta = 3/5. Find the possible values of p and q.

Why is p allowed to be negative yet q isn't??
Because is +ve so the angle is between and the +ve x-axis is anywhere between 0 and 180 degrees. This is precisely any point on the region .

Or differently to think about it, and since is +ve, q must be +ve.
3. (Original post by RDKGames)
Because is +ve so the angle is between and the +ve x-axis is anywhere between 0 and 180 degrees. This is precisely any point on the region .

Or differently to think about it, and since is +ve, q must be +ve.
Thanks, but may I ask what does the positive x-axis mean?
4. (Original post by dont know it)
Thanks, but may I ask what does the positive x-axis mean?
The positive portion of the x-axis. So the line
5. (Original post by RDKGames)
The positive portion of the x-axis. So the line
But then how can p=-6 as well as 6? If it's -6 doesn't that mean x<0?
6. (Original post by dont know it)
But then how can p=-6 as well as 6? If it's -6 doesn't that mean x<0?
The angle is measured from the +ve x-axis, it says nothing about the actual values being on the right side of the y-axis.
7. (Original post by RDKGames)
The angle is measured from the +ve x-axis, it says nothing about the actual values being on the right side of the y-axis.
Oh right I see. Thank you.

### Related university courses

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: March 12, 2018
Today on TSR

### Edexcel C3 Maths Unofficial Markscheme

Find out how you've done here

### 1,056

students online now

Exam discussions

Poll
Useful resources

### 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