# Is this a poorly worded question?

1. Jun 16, 2009

### rockyshephear

Example found on a website...(there were no graphs or explanations as to p or r or q)
Reverse engineering the question from the answer, I found p to be 180.
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A vector that has length 10 makes an angle of p/6 with the x-axis. Find its components.

Solution:

x = r cos q, y = r sin q

So that

x = (10)(/ 2), y = 10 (1/2) = 5

We can write the vector as

5 i + 5j

2. Jun 16, 2009

### slider142

They are using radian measure, and they meant p = $\pi$ radians which is equivalent to 180 degrees. Radian measure is derived from the unit circle; the radian measure of an angle is given by the length of arc that the angle subtends on a unit circle centered at the vertex of the angle. this makes use of the derived fact that the circumference of a circle is known to be 2$\pi$, so that 360 degrees is 2$\pi$ radians. It is common to leave off the "radian" as a unit of measure since it is also defined as a dimensionless ratio of two lengths (the length of arc divided by the length of the radius of the circle).

Last edited: Jun 16, 2009
3. Jun 16, 2009

### rockyshephear

Thanks

4. Jun 16, 2009

### Tibarn

Is it just me, or does that vector have neither the length nor the angle specified in the original problem?

5. Jun 17, 2009

### Irrational

yeah. answer is $$5\sqrt{3}i + 5j$$

$$\cos (\frac {\pi}{6}) = \frac{\sqrt3}{2}$$