# Need some clarification in regards to trigonometry

Need some clarification in regards to trigonometry....

## Homework Statement

For some reason, I am not seeing the cause of this. In attached problem 1, the Forces of x are described with a cos while forces of y are described with sin. In the second problem, the forces of X use sin and the forces of y use cos...... What am I missing here? Is there a certain topic I can review? Is it because of the quadrants they are in? the triangle they make (I would think obviously, I just don't see it :( )

Some of problem 1 has been cut off so I could attach the files

## Homework Equations

How do I figure out if I'm suppose to use a cos or a sin for x or y?

#### Attachments

• prob1.jpg
32.4 KB · Views: 341
• prob2.jpg
20.7 KB · Views: 367

I can't see your images yet, but I'm going to guess the problem is which angle you are using:

Consider a right angle triangle, with sides x, y and hypotenuse 1 (draw it!). Let's take the angle t to be between the sides x and 1: then cos(t)=adjacent/hypotenuse=x
sin(t)=opposite/hypotenuse=y

But if we take s to be the angle between 1 and y
sin(s)=opposite/hypotenuse=y

tiny-tim
Homework Helper
What am I missing here? Is there a certain topic I can review? Is it because of the quadrants they are in? the triangle they make

How do I figure out if I'm suppose to use a cos or a sin for x or y?

Hi r6mikey!