Period

Definition

In mathematics, the period of a function is the smallest positive value for which the function repeats its values. Understanding the period is crucial in the study of trigonometric functions, as it helps determine the behavior and repetition of these functions over the x-axis. This concept is also vital when working with inverse trigonometric functions, as their domains and ranges are often influenced by the periodicity of the original functions.

5 Must Know Facts For Your Next Test

1. The period of sine and cosine functions is $2\pi$, meaning they repeat every $2\pi$ units along the x-axis.
2. For tangent and cotangent functions, the period is $\pi$, indicating they repeat every $\pi$ units.
3. The secant and cosecant functions share the same period as their corresponding sine and cosine functions, respectively, which is $2\pi$.
4. When dealing with transformations of trigonometric functions, such as vertical stretches or shifts, the period may change depending on specific coefficients applied to the variable inside the function.
5. Inverse trigonometric functions, like arcsin and arccos, have restricted ranges due to their periodic nature; for instance, arcsin has a range of $[-\frac{\pi}{2}, \frac{\pi}{2}]$.

Review Questions

• How does understanding the period of trigonometric functions aid in solving equations involving these functions?
  • Knowing the period of trigonometric functions allows you to determine all possible solutions to equations that involve these functions by identifying where they repeat. For example, if you find one solution for sine within one period ($[0, 2\pi]$), you can generate additional solutions by adding integer multiples of the period, $2\pi$. This is crucial for accurately finding all angles that satisfy trigonometric equations.
• Compare and contrast the periods of sine, cosine, tangent, secant, cosecant, and cotangent functions.
  • Sine and cosine functions both have a period of $2\pi$, meaning they repeat every $2\pi$ units. In contrast, tangent and cotangent functions have a shorter period of $\pi$, repeating every $\pi$ units. Secant and cosecant share the same periods as their respective sine and cosine counterparts. Understanding these differences helps when graphing these functions and predicting their behavior over different intervals.
• Evaluate how changes in the coefficient of x affect the period of trigonometric functions, including an example.
  • When a coefficient is applied to x in a trigonometric function, it alters its period. For instance, in the function $f(x) = \sin(kx)$, where k is a positive constant, the new period becomes $\frac{2\pi}{k}$. If k = 2, then the period shortens to $\frac{2\pi}{2} = \pi$, causing the function to complete its cycle faster. This transformation impacts how we analyze and graph these functions.

Related terms

Amplitude:

The amplitude of a periodic function is the maximum distance that the function reaches from its midline, indicating the height of its peaks and the depth of its troughs.

Frequency:

Frequency refers to how many cycles a periodic function completes in a given interval, typically expressed in cycles per unit of time or space.

Phase Shift:

Phase shift is the horizontal shift left or right for periodic functions, affecting where the cycles begin on the x-axis.