4.5 Graphs of Sine and Cosine Functions

advertisement

4.5 Graphs of Sine and

Cosine Functions

Amplitude

Period

Translations

The graph of f(x)=sin x

Domain all Real numbers

Range -1 to 1

2

, 1

3

2

,

1

The graph of f(x)=sin x

Sin x is an odd function

3

2

, 1

2

, 1

 

2

,

1

3

2

,

1

Graph of f(x) = -sin x

Graph of the f(x) = Cos x

Domain: All real numbers

Range: -1 to 1

Graph of the f(x) = Cos x

Cos x is an even function

2

, 1

 

2

, 1

 

,

1

  

,

1

f ( x )

 cos( x )

 f ( x )

 sin

2 x

The red graph is Sin and the blue is Cos

Amplitude changes the Range

Amplitude changes the Range

Since Amplitude is a distance, it is always positive.

To find it: the absolute value of the Maximum minus the Minimum divide by two.

Amp is written before the function y = a*sin x

Amplitude changes the Range

Max 7; Min - 1 Amp. 7

(

1 )

4

2

2

, 7

 

,

1

2

Period (wave length)

The distance before the function repeats its value. y = sin bx; here b is 1.

Period (wave length) y = sin 2x b = 2

2

 period b

4

, 1

5

4

, 1

Translation to move the graph of the function y = sin (x + c): moves Right or Left

Here is y

 sin

2

Translation to move the graph of the function y = sin x + d moves up or down

Here is y

 sin x

2

With all the translations

The sine function is f(x) = d + a sin b(x +c)

The cosine function is f(x) = d + a cos b(x +c)

Applet for the Sine function

• http://www.analyzemath.com/trigonometry/ sine.htm

Homework

Page 307 – 310

#3, 9, 14, 20,

26, 32, 41, 49,

71, 78

Homework

Page 307 – 310

# 7, 12, 17, 23,

27, 36, 45, 60,

76, 86

Download