# Vector direction

1. Jun 24, 2008

### chukie

A helicopter is flying southeast with a speed of 200 m/s and the wind is blowing northeast with a speed of 60 m/s.

Which direction will the helicopter head now?
I know that u use tangent to solve for the angle. except im unsure whether it should be tan-1(200/60) or tan-1(60/600) and is the direction southeast?

Last edited: Jun 24, 2008
2. Jun 24, 2008

### Kurdt

Staff Emeritus
$$\tan \theta = \frac{o}{a}$$

where o = opposite side and a = adjacent side.

3. Jun 24, 2008

### chukie

yes i know except i don't know which angle to solve for. the one between the wind and the resultant or between the helicopter and the resultant?

4. Jun 24, 2008

### Kurdt

Staff Emeritus
It depends where the 0 angle is set. I would presume everything will be measured clockwise from North. If the question is not specific then you could just state where you've measured the angle from.

5. Jun 24, 2008

### chukie

i don't quite understand. do you mean that it doesnt matter which angle i find?

6. Jun 25, 2008

### Kurdt

Staff Emeritus
Which one will be the angle that will allow you to work out the angle from North?

7. Jun 25, 2008

### HallsofIvy

Staff Emeritus
To give the "direction" the helicopter will go you need to find the angle between NORTH and the vector representing the true path of the helicopter. Which angle in you diagram will give you that? What do the three vectors in your diagram represent and which shows the true path of the helicopter?

8. Jun 26, 2008

### chukie

oh okay thanks! i understand now!