If Sin(α) = 1/4 and Tan(α) = 0, what is the value of Cos(α)?

To solve for the value of Cos(α) given that Sin(α) = 1/4 and Tan(α) = 0, we can follow these steps:

  1. Understanding Tan(α):
    The tangent of an angle α is defined as the ratio of the sine to cosine:
    Tan(α) = Sin(α) / Cos(α)
    If Tan(α) = 0, it implies that Sin(α) = 0 or Cos(α) is undefined. However, in this case, we know that Sin(α) = 1/4, which means Cos(α) must be undefined. Hence, this would dictate that α is either at 0 degrees or 180 degrees since those angles yield a tangent of 0, where the sine value can still be defined.
  2. Using Pythagorean Identity:
    Regardless, we can still derive values using the Pythagorean identity for sine and cosine:
    Sin²(α) + Cos²(α) = 1
    Plugging in the known value of sine:
    (1/4)² + Cos²(α) = 1
    1/16 + Cos²(α) = 1
  3. Solving for Cos(α):
    Rearranging gives us:
    Cos²(α) = 1 - 1/16
    Cos²(α) = 16/16 - 1/16
    Cos²(α) = 15/16
    Taking the square root of both sides:
    Cos(α) = ±√(15/16)
    This simplifies to:
    Cos(α) = ±(√15)/4

Therefore, the possible values for Cos(α) are (√15)/4 or -(√15)/4, depending on the quadrant in which the angle α lies.

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