Bytelearn - cat image with glassesAI tutor

Welcome to Bytelearn!

Let’s check out your problem:

Use the reference angle to find the exact value of the given expression.\newlinecos(7π6)\cos \left(\frac{7\pi}{6}\right)

Full solution

Q. Use the reference angle to find the exact value of the given expression.\newlinecos(7π6)\cos \left(\frac{7\pi}{6}\right)
  1. Identify Reference Angle: Identify the reference angle for (7π)/6(7\pi)/6. Since (7π)/6(7\pi)/6 is in the third quadrant (more than π\pi but less than 3π/23\pi/2), the reference angle is π(7π)/6=(6π)/6(7π)/6=(π)/6\pi - (7\pi)/6 = (6\pi)/6 - (7\pi)/6 = -(\pi)/6.
  2. Determine Cosine: Determine the cosine of the reference angle.\newlineThe cosine of (π)/6(\pi)/6 is 3/2\sqrt{3}/2. Since the cosine is positive in the first quadrant and we are looking for the cosine of the negative of this angle, it remains positive: cos((π)/6)=cos((π)/6)=3/2\cos(-(\pi)/6) = \cos((\pi)/6) = \sqrt{3}/2.
  3. Apply Function Behavior: Apply the cosine function's behavior in different quadrants.\newlineIn the third quadrant, where (7π)/6(7\pi)/6 lies, the cosine function is negative. Therefore, we must take the negative of the reference angle's cosine value.
  4. Combine Results: Combine the results to find the exact value.\newlineThe exact value of cos(7π6)\cos\left(\frac{7\pi}{6}\right) is 3/2-\sqrt{3}/2.

More problems from Roots of rational numbers