y = asinx and y = sinbx.notebook
08.01.14
January 05, 2015
Lesson Starter
Using Desmos, investigate changing the value of a, b, c and d for the following graphs :
(a)
(b)
(c)
(d)
y = asinx
y = bcosx
y = sincx
y = cosdx
1
y = asinx and y = sinbx.notebook
08.01.14
January 05, 2015
Learning Intention
2
y = asinx and y = sinbx.notebook
January 05, 2015
08.01.14 Graphs of y = asinx and y = sinbx
Sketching Trigonometric Graphs
Sketching a graph does not require an accurate plot.
It is more straightforward to sketch graphs in the following order :
y
1) Draw a set of axes
x
y
2) Draw the basic shape of the curve
x
y
1
3) Fill in the important values
0
90
180 270 360
x
­1
y = asinx and y = acosx
Changing the value of the variable a stretches or compresses the graph in the y­direction. It does not affect the x­direction.
Examples
1) State the equation of the blue curve each time.
(a)
(b)
(c)
2) Sketch the following graphs, for 0 ≤ xo ≤ 360
(a)
y = 3sinx
(b)
1
y = cosx
2
(c)
y = ­2sinx
3
y = asinx and y = sinbx.notebook
January 05, 2015
y = sinbx and y = cosbx
Changing the value of the variable a stretches or compresses the graph in the x­direction. It does not affect the y­direction.
Examples
1) State the equation of this graph
2) Sketch the following graphs, for 0 ≤ xo ≤ 360
(a)
y = sin3x
(b)
y = cos2x
1
2
4
y = asinx and y = sinbx.notebook
January 05, 2015
Classwork
Leckie & Leckie N5
Success Criteria
Page 253­255
Ex 23A
Ex 23B
Work with graph of trigonometric functions
N5 Relationships
5