How to find the range of the sine
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ACT Math › How to find the range of the sine
Which of the following represents a sine wave with a range of ?
Explanation
The range of a sine wave is altered by the coefficient placed in front of the base equation. So, if you have , this means that the highest point on the wave will be at 
 and the lowest at 
. However, if you then begin to shift the equation vertically by adding values, as in, 
, then you need to account for said shift. This would make the minimum value to be 
 and the maximum value to be 
. For our question, then, it is fine to use 
. The 
 for the function parameter only alters the period of the equation, making its waves "thinner."
Which of the following statements is (are) true:
I. The domain of the tangent function is all real numbers
II. The range of the sine function is all real numbers
III. The periods of the tangent, sine, and cosine functions are the same.
I only
II only
I and II only
II and III only
none of the above
Explanation
The domain of the tangent function does not include any values of x that are odd multiples of π/2 .
The range of the sine function is from \[-1, 1\].
The period of the tangent function is π, whereas the period for both sine and cosine is 2π.
What is the range of the following trigonometric equation:
?
Explanation
The range of a sine or cosine function spans from the negative amplitude to the positive amplitude. The amplitude is  in the general formula: 
Thus we see amplitude of our function is  and so the range is:
What is the range of the trigonometric function given by the equation:
Explanation
The range of the sine and cosine functions are the closed interval from the negative amplitude and the positive amplitude. The amplitude is given by the coefficient,  in the following general equation:
. Thus we see the range is:
Which of the following sine waves has a range of  to 
?
Explanation
The range of a sine wave is altered by the coefficient placed in front of the base equation. So, if you have , this means that the highest point on the wave will be at 
 and the lowest at 
; however, if you then begin to shift the equation vertically by adding values, as in, 
, then you need to account for said shift. This would make the minimum value to be 
 and the maximum value to be 
.
For our question, the range of values covers . This range is accomplished by having either 
 or 
 as your coefficient. (
 merely flips the equation over the 
-axis. The range "spread" remains the same.) We need to make the upper value to be 
 instead of 
. To do this, you will need to add 
 to 
. This requires an upward shift of 
. An example of performing a shift like this is:
Among the possible answers, the one that works is:
The  parameter does not matter, as it only alters the frequency of the function.