Given information: y=3sin(x+π)
Concept Involved:
Amplitude:
The constant factor a in y=asinx and y=acosx as a scaling factor − a vertical stretch or vertical shrink of the basic curve. When |a|>1, the basic curve is stretched, and when 0<|a|<1, the basic curve is shrunk. The result is that the graphs of y=asinx and y=acosx range between –a and a instead of between −1 and 1 . The absolute value of a is the amplitude of the function. The range of the function for a>0 is −a≤y≤a .
The amplitude of y=asinx and y=acosx represents half the distance between the maximum and the minimum values of the function and is given by Amplitude=|a| .
Period:
Let b be a positive real number.
The period y=asinbx and y=acosbx is given by Period=2π/b
Note that when 0<b<1, the period of y=asinbx is greater than 2π and represents a horizontal stretch of the basic curve. Similarly, when b>1, the period of y=asinbx is less than 2π and represents a horizontal shrink of the basic curve. These two statements are also true for y=acosbx . When b is negative, rewrite the function using the identify sin(−x)=−sinx or cos(−x)=cosx .
Horizontal Translation:
The constant c in the equation y=asin(bx−c) and y=acos(bx−c) results in horizontal translations (shifts) of the basics curves. For example, compare the graphs of y=asinbx & y=asin(bx−c) . The graph of y=asin(bx−c) completes one cycle from bx−c=0 to bx−c=2π . Solve for x to find that interval for one cycle is c/b ︷Left endpoint≤x≤c/b + 2π/b ︸Period ︷Right endpoint . This implies that the period of y=asin(bx−c) is 2π/b , and the graph of y=asinbx is shifted by an amount c/b . Phase Shift=c/b .
Vertical Translation:
The constant d in the equation y=asin(bx−c)+d and y=acos(bx−c)+d results in vertical translations of the basic curves. The shift is d units up for d>0 and d units down for d<0. In other words, the graph oscillates about the horizontal line y=d instead of about the x- axis.
Calculation:
Rewrite the given function y=3sin(x−(−π)) in the form y=asin(bx−c)+d
y=3sin(1x−(−π))+0
Identify a, b, c, & d of our given function by comparing it with y=asin(bx−c)+d
a=3 ; b=1 ; c=−π ; d=0
Identify Amplitude, Period, Phase shift {Horizontal Shift}, Vertical shift& mid-line
Amplitude is |a| | Period is 2π/b | Phase shift is c/b | Vertical Shift is d | Mid-line of function |
|3|=3 | 2π1=2π | cb=−π1 =−π | d=0 | y=0 |
Graph:
Interpretation:
The graph of the function y=3sin(x+π) has one complete cycle in the interval (−π, π) .It has a midline y=0 , has amplitude as 3, maximum height of the function 3 andminimum height of the function is -3. The start point {Left end} of the graph would be −π & the end point of one complete cycle is π .