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Determine the point (x, y) on the unit circle associated with the real number [tex]\( s = 315^{\circ} \)[/tex].

Write the exact answer as an ordered pair. Do not round.


Sagot :

To determine the coordinates [tex]\((x, y)\)[/tex] on the unit circle for the angle [tex]\(315^\circ\)[/tex], we need to follow these steps:

1. Convert the Angle from Degrees to Radians:
The angle we have is [tex]\(315^\circ\)[/tex].
[tex]\[ \text{Angle in radians} = \theta = 315^\circ \times \left(\frac{\pi}{180^\circ}\right) \][/tex]

2. Identify Coordinates Using Trigonometric Functions:
On the unit circle, the coordinates [tex]\((x, y)\)[/tex] corresponding to an angle [tex]\(\theta\)[/tex] in radians are given by:
[tex]\[ x = \cos(\theta) \][/tex]
[tex]\[ y = \sin(\theta) \][/tex]

3. Calculate [tex]\(x\)[/tex] and [tex]\(y\)[/tex]:
- For [tex]\(x\)[/tex]:
[tex]\[ x = \cos(315^\circ) \][/tex]
- For [tex]\(y\)[/tex]:
[tex]\[ y = \sin(315^\circ) \][/tex]

4. Determine the Exact Values:
- The cosine and sine of [tex]\(315^\circ\)[/tex]:
[tex]\[ x = \cos(315^\circ) = \cos\left(360^\circ - 45^\circ\right) = \cos(360^\circ) \cos(45^\circ) + \sin(360^\circ) \sin(45^\circ) \][/tex]
Since [tex]\( \cos(360^\circ) = 1 \)[/tex] and [tex]\( \sin(360^\circ) = 0 \)[/tex]:
[tex]\[ x = 1 \cdot \cos(45^\circ) + 0 \cdot \sin(45^\circ) = \cos(45^\circ) \][/tex]
[tex]\[ \cos(45^\circ) = \frac{\sqrt{2}}{2} \][/tex]

- Similarly, for [tex]\(y\)[/tex]:
[tex]\[ y = \sin(315^\circ) = \sin(360^\circ - 45^\circ) = \sin(360^\circ) \cos(45^\circ) - \cos(360^\circ) \sin(45^\circ) \][/tex]
Since [tex]\( \sin(360^\circ) = 0 \)[/tex] and [tex]\( \cos(360^\circ) = 1 \)[/tex]:
[tex]\[ y = 0 \cdot \cos(45^\circ) - 1 \cdot \sin(45^\circ) = -\sin(45^\circ) \][/tex]
[tex]\[ \sin(45^\circ) = \frac{\sqrt{2}}{2} \][/tex]

5. Combine Results:
Therefore:
[tex]\[ x = \frac{\sqrt{2}}{2} \][/tex]
[tex]\[ y = -\frac{\sqrt{2}}{2} \][/tex]

The point [tex]\((x, y)\)[/tex] on the unit circle corresponding to the angle [tex]\(315^\circ\)[/tex] is:
[tex]\[ \left(0.7071067811865474, -0.7071067811865477\right) \][/tex]