Determine two pairs of polar coordinates for [tex]$(3, -3)$[/tex] when [tex]$0^{\circ} \ \textless \ \theta \ \textless \ 360^{\circ}$[/tex].

A. [tex]\left(3 \sqrt{2}, 45^{\circ}\right),\left(-3 \sqrt{2}, 225^{\circ}\right)[/tex]
B. [tex]\left(3 \sqrt{2}, 315^{\circ}\right),\left(-3 \sqrt{2}, 135^{\circ}\right)[/tex]
C. [tex]\left(3 \sqrt{2}, 135^{\circ}\right),\left(-3 \sqrt{2}, 315^{\circ}\right)[/tex]
D. [tex]\left(3 \sqrt{2}, 225^{\circ}\right),\left(-3 \sqrt{2}, 45^{\circ}\right)[/tex]

Please select the best answer from the choices provided:
A, B, C, or D



Answer :

To determine two pairs of polar coordinates for the point [tex]\((3, -3)\)[/tex] when [tex]\(0^{\circ} < \theta < 360^{\circ}\)[/tex], we need to follow a few steps.

### Step 1: Convert Cartesian Coordinates to Polar Coordinates

First, we need to convert the Cartesian coordinates [tex]\((3, -3)\)[/tex] into polar form [tex]\((r, \theta)\)[/tex]. The polar coordinates are determined as follows:

1. Magnitude (r):
[tex]\[ r = \sqrt{x^2 + y^2} \][/tex]
Substituting [tex]\(x = 3\)[/tex] and [tex]\(y = -3\)[/tex]:
[tex]\[ r = \sqrt{3^2 + (-3)^2} = \sqrt{9 + 9} = \sqrt{18} = 3\sqrt{2} \][/tex]

2. Angle ([tex]\(\theta\)[/tex]):
[tex]\[ \theta = \tan^{-1}\left(\frac{y}{x}\right) \][/tex]
Substituting [tex]\(x = 3\)[/tex] and [tex]\(y = -3\)[/tex]:
[tex]\[ \theta = \tan^{-1}\left(\frac{-3}{3}\right) = \tan^{-1}(-1) \][/tex]

The value of [tex]\(\tan^{-1}(-1)\)[/tex] is [tex]\(-45^\circ\)[/tex], but we must convert this to a positive angle within [tex]\(0^{\circ} < \theta < 360^{\circ}\)[/tex]. Since the point [tex]\((3, -3)\)[/tex] is in the fourth quadrant:
[tex]\[ \theta = 360^\circ - 45^\circ = 315^\circ \][/tex]

### Step 2: Determine the Two Pairs

In polar coordinates, the point [tex]\((r, \theta)\)[/tex] can also be represented as [tex]\((-r, \theta + 180^\circ)\)[/tex], where [tex]\(\theta + 180^\circ\)[/tex] must also be within [tex]\(0^{\circ} < \theta < 360^{\circ}\)[/tex].

1. First Pair:
[tex]\[ (r, \theta) = \left(3\sqrt{2}, 315^\circ\right) \][/tex]

2. Second Pair:
[tex]\[ (-r, \theta + 180^\circ) \][/tex]
Since [tex]\(\theta = 315^\circ\)[/tex]:
[tex]\[ \theta + 180^\circ = 315^\circ + 180^\circ = 495^\circ \][/tex]
We need to convert [tex]\(495^\circ\)[/tex] to a value within [tex]\(0^{\circ} < \theta < 360^{\circ}\)[/tex]:
[tex]\[ 495^\circ - 360^\circ = 135^\circ \][/tex]

So the second pair is:
[tex]\[ \left(-3\sqrt{2}, 135^\circ\right) \][/tex]

### Step 3: Compare with Given Choices

Now, we compare our results with the given choices:
- a. [tex]\(\left(3 \sqrt{2}, 45^{\circ}\right),\left(-3 \sqrt{2}, 225^{\circ}\right)\)[/tex]
- b. [tex]\(\left(3 \sqrt{2}, 315^{\circ}\right),\left(-3 \sqrt{2}, 135^{\circ}\right)\)[/tex]
- c. [tex]\(\left(3 \sqrt{2}, 135^{\circ}\right),\left(-3 \sqrt{2}, 315^{\circ}\right)\)[/tex]
- d. [tex]\(\left(3 \sqrt{2}, 225^{\circ}\right),\left(-3 \sqrt{2}, 45^{\circ}\right)\)[/tex]

### Conclusion

The correct pair of polar coordinates for [tex]\((3, -3)\)[/tex] is:
- [tex]\(\left(3 \sqrt{2}, 315^{\circ}\right), \left(-3 \sqrt{2}, 135^{\circ}\right)\)[/tex]

Thus, the best answer is:
B.