Respuesta :

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Answer:

 [tex]-\frac{\sqrt2}{2} \\[/tex]  or exact is −0.70710678...

Step-by-step explanation:

Getting the point!

  1. If we look at the unit circle and we find [tex]-\frac{3\pi }{4}[/tex] we see it is in the 3rd quadrant.
  2. We know that all points in the 3rd quadrant have both negative x and negative y values.
  3. We know that all radians with the base of 4 on the unit circle have the points of [tex](\frac{\sqrt{2}}{2} ,\frac{\sqrt{2}}{2})[/tex]
  4. Because we are in the 3rd quadrant and both x and y are negative we know the point of [tex]-\frac{3\pi }{4}[/tex]  is [tex](-\frac{\sqrt{2}}{2}, -\frac{\sqrt{2}}{2})[/tex]

Finding the sin!

  1. Because we know that sin is asking us for the y value
  2. We can just look at the point and find the y value!
  3. the y value is [tex]-\frac{\sqrt2}{2} \\[/tex]
  4. Because this fraction does not need to be rationalized we are good!
  5. Use a calculator to find the exact value and you get -0.70710678...
  6. The final answer is  [tex]-\frac{\sqrt2}{2} \\[/tex] or exact is −0.70710678...

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