Math Problem Statement

find sin of 7pi/6 using unit circle

Solution

To find sin(7π6)\sin\left(\frac{7\pi}{6}\right) using the unit circle, follow these steps:

  1. Identify the reference angle:
    The angle 7π6\frac{7\pi}{6} is in radians. First, subtract π\pi (or 6π6\frac{6\pi}{6}) from 7π6\frac{7\pi}{6} to find the reference angle: 7π6π=7π66π6=π6\frac{7\pi}{6} - \pi = \frac{7\pi}{6} - \frac{6\pi}{6} = \frac{\pi}{6} So, the reference angle is π6\frac{\pi}{6}.

  2. Determine the quadrant:
    The angle 7π6\frac{7\pi}{6} is slightly more than π\pi, placing it in the third quadrant. In the third quadrant, the sine function is negative.

  3. Find the sine of the reference angle:
    The reference angle is π6\frac{\pi}{6}, and from the unit circle, we know: sin(π6)=12\sin\left(\frac{\pi}{6}\right) = \frac{1}{2}

  4. Apply the sign based on the quadrant:
    Since sin\sin is negative in the third quadrant, the sine of 7π6\frac{7\pi}{6} is: sin(7π6)=12\sin\left(\frac{7\pi}{6}\right) = -\frac{1}{2}

Final Answer:

sin(7π6)=12\sin\left(\frac{7\pi}{6}\right) = -\frac{1}{2}

Would you like further details or have any questions about this?

Here are five related questions:

  1. What is the cosine of 7π6\frac{7\pi}{6}?
  2. How do you find the tangent of 7π6\frac{7\pi}{6}?
  3. What is the sine of 11π6\frac{11\pi}{6}?
  4. How do the coordinates of points on the unit circle relate to sine and cosine values?
  5. What is the general formula for sine in different quadrants?

Tip: In the unit circle, sine corresponds to the y-coordinate of the point on the circle.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Unit Circle
Sine Function
Reference Angles
Quadrants

Formulas

sin(θ) = y-coordinate of the point on the unit circle
Reference angle formula: θ - π (for third quadrant)

Theorems

Unit Circle Theorem
Sine Function Behavior in Different Quadrants

Suitable Grade Level

Grades 9-12