# Sin/Cos In Equation

1. Jan 1, 2012

### Let It Be

1. Trying to understand how to work a given angle into an answer in projectile motion problems.

2. ΔX=ViTf+1/2ATf^2
R=2vi^2sinθcosθ/g

3. Well, I know if you're given say 45° then you would use sin for vertical and cos for horizontal. But beyond that, what are you supposed to do with an angle when given one.

ALSO:
For the first equation, do you substitute Vi for Visinθ or Vicosθ?

2. Jan 1, 2012

### SammyS

Staff Emeritus
It depends upon how θ is defined ! (Answer to both questions)

3. Jan 1, 2012

### Let It Be

Can you explain a little more on that?

4. Jan 2, 2012

### SammyS

Staff Emeritus
Sure.