Introduction to
Trigonometric
Functions
(Sine and Cosine)
1. The Basics of Trigonometry
Contents
2. Construction of the Unit Circle
3. Relationship of the Unit Circle to the Sine & Cosine Functions
4. Basic Properties of the Sine & Cosine Functions
5. Parent and Transformed Sine & Cosine Functions
1. The Basics of Trigonometry
The study of the relationships
between the lengths and
angles of triangles.
Trigonometry – from the 2 Greek
words  trigonon – “triangle" and
metron – “measure”
for Right Triangles
1. The Basics of Trigonometry
All you really need to know is:
S O H C A
H
T O
A
1. The Basics of Trigonometry
Definitions – 3 Most Common Trig Ratios
S O H C A
H
T O A
Sine Cosine Tangent
Opposite Opposite
Hypotenuse Hypotenuse
Adjacent
Adjacent
𝑺=
𝑶
𝑯
or or
𝑪=
𝑨
𝑯
or
𝑻 =
𝑶
𝑨
Triangle Labelling
Step 1 Label the REFERENCE ANGLE,
𝜽
Step 2 Label the HYPOTENUSE, “H”
𝐇
Note: the HYPOTENUSE is always across
from the 90 degree symbol box in the
triangle and is longest side of the triangle.
Step 3 Label the
OPPOSITE side, “O”
𝐎
Note: the OPPOSITE
side is always across
from the REFERENCE
ANGLE.
Step 4 Label the
ADJACENT side, “A”
𝐀 Note: the ADJACENT side is always
beside or next to the REFERENCE ANGLE.
1. The Basics of Trigonometry
𝒓
=
𝟏
The radius of the Unit
Circle is .
𝒓
=
𝟏
𝒓
=
𝟏
𝒓
=
𝟏
The degrees around the Unit Circle are noted at each of the Special Triangle intersection points on the circle.
𝟑𝟎°
𝟎°
𝟒𝟓°
𝟔𝟎°
𝟗𝟎°
𝟏𝟐𝟎°
𝟏𝟑𝟓°
𝟏𝟓𝟎°
𝟏𝟖𝟎°
𝟐𝟏𝟎°
𝟐𝟐𝟓°
𝟐𝟒𝟎°
𝟐𝟕𝟎°
𝟑𝟎𝟎°
𝟑𝟏𝟓°
𝟑𝟑𝟎°
/
2. Construction of the Unit Circle (Degrees)
𝒓
=
𝟏
𝒓
=
𝟏
𝒓
=
𝟏
𝒓
=
𝟏
2. Construction of the Unit Circle (Radians)
The radians around the Unit Circle are noted at each of the Special Triangle intersection points on the
The radius of the Unit
Circle is .
𝝅
𝟔
𝝅
𝟒
𝝅
𝟑
𝝅
𝟐
𝟐𝝅
𝟑
𝟑𝝅
𝟒
𝟓𝝅
𝟔
𝝅
𝟕𝝅
𝟔
𝟓𝝅
𝟒 𝟒 𝝅
𝟑 𝟑𝝅
𝟐
𝟓𝝅
𝟑
𝟕𝝅
𝟒
𝟏𝟏𝝅
𝟔
𝟐𝝅
/
𝒓
=
𝟏
𝒓
=
𝟏
𝒓
=
𝟏
𝒓
=
𝟏
2. Construction of the Unit Circle (Coordinates)
The coordinates around the Unit Circle are noted at each of
the Special Triangle intersection points on the circle.
(√𝟐
𝟐
, √𝟐
𝟐 )
The radius of the Unit
Circle is .
(−
√𝟐
𝟐
,
√𝟐
𝟐 )
(−
√𝟐
𝟐
,−
√𝟐
𝟐 ) (√𝟐
𝟐
,−
√𝟐
𝟐 )
(√𝟑
𝟐
,
𝟏
𝟐)
(− √𝟑
𝟐
,
𝟏
𝟐)
(− √𝟑
𝟐
,−
𝟏
𝟐 ) (√𝟑
𝟐
,−
𝟏
𝟐)
(𝟏
𝟐
,
√𝟑
𝟐 )
(−
𝟏
𝟐
, √𝟑
𝟐 )
(−
𝟏
𝟐
,− √𝟑
𝟐 ) (𝟏
𝟐
,− √𝟑
𝟐 )
(𝟏 , 𝟎)
(𝟎 , 𝟏)
(−𝟏,𝟎)
(𝟎,−𝟏)
https://www.desmos.com/calculator/cpb0oammx7
𝟎
𝝅
𝟐
𝟑𝝅
𝟐
𝝅 𝟐 𝝅 𝟓𝝅
𝟐
𝒓 =𝟏
3. Relationship of the Unit Circle with the Sine Function
𝟎/𝟐𝝅
𝝅
𝟐
𝝅
𝟑𝝅
𝟐
𝟏
−𝟏
If you peel apart
this Unit Circle.
You get this trigonometric
Sine Function
Click on this link to view the
interactive Unit Circle and Sine and
Cosine Trig Functions on Desmos.
x sin(x)
0 0
1
0
-1
0
https://www.desmos.com/calculator/cpb0oammx7
𝟎
𝝅
𝟐
𝟑𝝅
𝟐
𝝅 𝟐 𝝅 𝟓𝝅
𝟐
𝒓 =𝟏
3. Relationship of the Unit Circle with the Cosine Function
𝟎/𝟐𝝅
𝝅
𝟐
𝝅
𝟑𝝅
𝟐
𝟏
−𝟏
If you peel apart
this Unit Circle.
You get this trigonometric
Cosine Function
Click on this link to view the
interactive Unit Circle and Sine and
Cosine Trig Functions on Desmos.
x cos(x)
0 1
0
-1
0
1
Copyright © by Houghton Mifflin Company, Inc. All
rights reserved.
12
4. The cycle repeats itself indefinitely in both directions of
the x-axis.
The graphs of the parent functions y = sin x and y = cos x
have similar properties:
1. The maximum value is 1 and the minimum value is –1.
2. Each graph is a smooth curve.
3. Each function cycles through all the values of the range
over an x-interval of .
4. Basic Properties of the Sine & Cosine Functions
Max
Min
4. Basic Properties of the Sine & Cosine Functions
 Amplitude 
This is the
Amplitude of
the Function
The amplitude of the sine or cosine
function is the distance from the midline
or center of the curve to either the peak
(top) or the trough (bottom) of the curve.
The amplitude is equal to ½ of
the distance between the
Maximum Point and the
Minimum Point of the curve.
This is the
Maximum Point
of the Function
This is the
Minimum Point of
the Function
This is the
Midline of
the Function
Y - Axis
X - Axis
The amplitude
is equal to ½
this distance.
Copyright © by Houghton Mifflin Company, Inc. All
rights reserved.
14
The amplitude of y = a sin x (or y = a cos x) is half the distance
between the maximum and minimum values of the function and
is always a positive value (hence the absolute value symbol).
Amplitude = |a|
If , the amplitude stretches the graph vertically.
If , the amplitude shrinks the graph vertically.
If has a negative sign in front of it like  , the amplitude is
still positive (as distances are always positive), but the graph is
reflected across the x-axis.
4. Basic Properties of the Sine & Cosine Functions
 Amplitude 
4. Basic Properties of the Sine & Cosine Functions
 Period 
This distance
is the Period of
the Function
The sine and cosine functions consist
of identical, repeating sections called
periods that form a wave-like pattern.
The period of a function is the
horizontal length of one
complete cycle.
This distance is
the Period of the
Function
This is the
Midline of
the Function
Y - Axis
X - Axis
4. Basic Properties of the Sine & Cosine Functions
 Midline 
The midline of the sine or cosine
function is the horizontal line
where the function fluctuates an
equal amount above and below it.
This is the Midline of
the Cosine Function
Note that the midline of a function will change if there is
a vertical translation of the graph. For example, the
midline of the upper graph is located at y = 3.
X - Axis
Y - Axis
This is the Midline of the
this Cosine Function
The midline is parallel to the x-
axis and is located ½ the distance
between the graphs maximum
and minimum values.
This is the amount the upper graph
translated up from the lower graph
1
2
3
4
0
and
5. Parent and Transformed Sine & Cosine Functions
Parent Sine Function is:
Transformed Sine Function is:
Parent Cosine Function
is:
Transformed Cosine Function is:
is the Vertical Translation
of the graph and is also
the midline.
5. Parent and Transformed Sine & Cosine Functions
𝒇 (𝒙)𝒐𝒓 𝒚=𝒂 𝒔𝒊𝒏 𝒃(𝒙 −𝒄)+𝒅
is the Amplitude which
stretches or shrinks the graph
vertically or reflects (flips) it if
there is a negative sign in front
of the positive amplitude value.
is used to find the Period or number
of times the graph will repeat during
its normal interval. It compresses or
stretches the graph horizontally.
The Period is equal to:
is the Horizontal
Translation or Phase
Shift of the graph.
5. Parent and Transformed Sine & Cosine Functions
𝒇 (𝒙)𝒐𝒓 𝒚=𝒂 𝒔𝒊𝒏(𝒃 𝒙 −𝒄)+𝒅
One comment on “Phase Shift” of the function
Sometimes is located inside the
parentheses. This will affect the value
for the Phase Shift of the function.
To find the actual Phase Shift of the function, you have to move the outside of
the parentheses and adjust the value of “c” inside the parentheses. This
adjusted value will provide the correct value for the Phase Shift of the function.
𝒇 ( 𝒙) 𝒐𝒓 𝒚=𝒂 𝒔𝒊𝒏 𝒃(𝒙 −
𝒄
𝒃 )+𝒅
This is normally the Phase
Shift value when “b” is
outside the parentheses
in the original function.
Phase Shift
is
𝒃
𝒃 𝒃

IntroductiontoTrigonometricFunctionsSineandCosine-1.pptx

  • 1.
  • 2.
    1. The Basicsof Trigonometry Contents 2. Construction of the Unit Circle 3. Relationship of the Unit Circle to the Sine & Cosine Functions 4. Basic Properties of the Sine & Cosine Functions 5. Parent and Transformed Sine & Cosine Functions
  • 3.
    1. The Basicsof Trigonometry The study of the relationships between the lengths and angles of triangles. Trigonometry – from the 2 Greek words  trigonon – “triangle" and metron – “measure” for Right Triangles
  • 4.
    1. The Basicsof Trigonometry All you really need to know is: S O H C A H T O A
  • 5.
    1. The Basicsof Trigonometry Definitions – 3 Most Common Trig Ratios S O H C A H T O A Sine Cosine Tangent Opposite Opposite Hypotenuse Hypotenuse Adjacent Adjacent 𝑺= 𝑶 𝑯 or or 𝑪= 𝑨 𝑯 or 𝑻 = 𝑶 𝑨
  • 6.
    Triangle Labelling Step 1Label the REFERENCE ANGLE, 𝜽 Step 2 Label the HYPOTENUSE, “H” 𝐇 Note: the HYPOTENUSE is always across from the 90 degree symbol box in the triangle and is longest side of the triangle. Step 3 Label the OPPOSITE side, “O” 𝐎 Note: the OPPOSITE side is always across from the REFERENCE ANGLE. Step 4 Label the ADJACENT side, “A” 𝐀 Note: the ADJACENT side is always beside or next to the REFERENCE ANGLE. 1. The Basics of Trigonometry
  • 7.
    𝒓 = 𝟏 The radius ofthe Unit Circle is . 𝒓 = 𝟏 𝒓 = 𝟏 𝒓 = 𝟏 The degrees around the Unit Circle are noted at each of the Special Triangle intersection points on the circle. 𝟑𝟎° 𝟎° 𝟒𝟓° 𝟔𝟎° 𝟗𝟎° 𝟏𝟐𝟎° 𝟏𝟑𝟓° 𝟏𝟓𝟎° 𝟏𝟖𝟎° 𝟐𝟏𝟎° 𝟐𝟐𝟓° 𝟐𝟒𝟎° 𝟐𝟕𝟎° 𝟑𝟎𝟎° 𝟑𝟏𝟓° 𝟑𝟑𝟎° / 2. Construction of the Unit Circle (Degrees)
  • 8.
    𝒓 = 𝟏 𝒓 = 𝟏 𝒓 = 𝟏 𝒓 = 𝟏 2. Construction ofthe Unit Circle (Radians) The radians around the Unit Circle are noted at each of the Special Triangle intersection points on the The radius of the Unit Circle is . 𝝅 𝟔 𝝅 𝟒 𝝅 𝟑 𝝅 𝟐 𝟐𝝅 𝟑 𝟑𝝅 𝟒 𝟓𝝅 𝟔 𝝅 𝟕𝝅 𝟔 𝟓𝝅 𝟒 𝟒 𝝅 𝟑 𝟑𝝅 𝟐 𝟓𝝅 𝟑 𝟕𝝅 𝟒 𝟏𝟏𝝅 𝟔 𝟐𝝅 /
  • 9.
    𝒓 = 𝟏 𝒓 = 𝟏 𝒓 = 𝟏 𝒓 = 𝟏 2. Construction ofthe Unit Circle (Coordinates) The coordinates around the Unit Circle are noted at each of the Special Triangle intersection points on the circle. (√𝟐 𝟐 , √𝟐 𝟐 ) The radius of the Unit Circle is . (− √𝟐 𝟐 , √𝟐 𝟐 ) (− √𝟐 𝟐 ,− √𝟐 𝟐 ) (√𝟐 𝟐 ,− √𝟐 𝟐 ) (√𝟑 𝟐 , 𝟏 𝟐) (− √𝟑 𝟐 , 𝟏 𝟐) (− √𝟑 𝟐 ,− 𝟏 𝟐 ) (√𝟑 𝟐 ,− 𝟏 𝟐) (𝟏 𝟐 , √𝟑 𝟐 ) (− 𝟏 𝟐 , √𝟑 𝟐 ) (− 𝟏 𝟐 ,− √𝟑 𝟐 ) (𝟏 𝟐 ,− √𝟑 𝟐 ) (𝟏 , 𝟎) (𝟎 , 𝟏) (−𝟏,𝟎) (𝟎,−𝟏)
  • 10.
    https://www.desmos.com/calculator/cpb0oammx7 𝟎 𝝅 𝟐 𝟑𝝅 𝟐 𝝅 𝟐 𝝅𝟓𝝅 𝟐 𝒓 =𝟏 3. Relationship of the Unit Circle with the Sine Function 𝟎/𝟐𝝅 𝝅 𝟐 𝝅 𝟑𝝅 𝟐 𝟏 −𝟏 If you peel apart this Unit Circle. You get this trigonometric Sine Function Click on this link to view the interactive Unit Circle and Sine and Cosine Trig Functions on Desmos. x sin(x) 0 0 1 0 -1 0
  • 11.
    https://www.desmos.com/calculator/cpb0oammx7 𝟎 𝝅 𝟐 𝟑𝝅 𝟐 𝝅 𝟐 𝝅𝟓𝝅 𝟐 𝒓 =𝟏 3. Relationship of the Unit Circle with the Cosine Function 𝟎/𝟐𝝅 𝝅 𝟐 𝝅 𝟑𝝅 𝟐 𝟏 −𝟏 If you peel apart this Unit Circle. You get this trigonometric Cosine Function Click on this link to view the interactive Unit Circle and Sine and Cosine Trig Functions on Desmos. x cos(x) 0 1 0 -1 0 1
  • 12.
    Copyright © byHoughton Mifflin Company, Inc. All rights reserved. 12 4. The cycle repeats itself indefinitely in both directions of the x-axis. The graphs of the parent functions y = sin x and y = cos x have similar properties: 1. The maximum value is 1 and the minimum value is –1. 2. Each graph is a smooth curve. 3. Each function cycles through all the values of the range over an x-interval of . 4. Basic Properties of the Sine & Cosine Functions
  • 13.
    Max Min 4. Basic Propertiesof the Sine & Cosine Functions  Amplitude  This is the Amplitude of the Function The amplitude of the sine or cosine function is the distance from the midline or center of the curve to either the peak (top) or the trough (bottom) of the curve. The amplitude is equal to ½ of the distance between the Maximum Point and the Minimum Point of the curve. This is the Maximum Point of the Function This is the Minimum Point of the Function This is the Midline of the Function Y - Axis X - Axis The amplitude is equal to ½ this distance.
  • 14.
    Copyright © byHoughton Mifflin Company, Inc. All rights reserved. 14 The amplitude of y = a sin x (or y = a cos x) is half the distance between the maximum and minimum values of the function and is always a positive value (hence the absolute value symbol). Amplitude = |a| If , the amplitude stretches the graph vertically. If , the amplitude shrinks the graph vertically. If has a negative sign in front of it like  , the amplitude is still positive (as distances are always positive), but the graph is reflected across the x-axis. 4. Basic Properties of the Sine & Cosine Functions  Amplitude 
  • 15.
    4. Basic Propertiesof the Sine & Cosine Functions  Period  This distance is the Period of the Function The sine and cosine functions consist of identical, repeating sections called periods that form a wave-like pattern. The period of a function is the horizontal length of one complete cycle. This distance is the Period of the Function This is the Midline of the Function Y - Axis X - Axis
  • 16.
    4. Basic Propertiesof the Sine & Cosine Functions  Midline  The midline of the sine or cosine function is the horizontal line where the function fluctuates an equal amount above and below it. This is the Midline of the Cosine Function Note that the midline of a function will change if there is a vertical translation of the graph. For example, the midline of the upper graph is located at y = 3. X - Axis Y - Axis This is the Midline of the this Cosine Function The midline is parallel to the x- axis and is located ½ the distance between the graphs maximum and minimum values. This is the amount the upper graph translated up from the lower graph 1 2 3 4 0
  • 17.
    and 5. Parent andTransformed Sine & Cosine Functions Parent Sine Function is: Transformed Sine Function is: Parent Cosine Function is: Transformed Cosine Function is:
  • 18.
    is the VerticalTranslation of the graph and is also the midline. 5. Parent and Transformed Sine & Cosine Functions 𝒇 (𝒙)𝒐𝒓 𝒚=𝒂 𝒔𝒊𝒏 𝒃(𝒙 −𝒄)+𝒅 is the Amplitude which stretches or shrinks the graph vertically or reflects (flips) it if there is a negative sign in front of the positive amplitude value. is used to find the Period or number of times the graph will repeat during its normal interval. It compresses or stretches the graph horizontally. The Period is equal to: is the Horizontal Translation or Phase Shift of the graph.
  • 19.
    5. Parent andTransformed Sine & Cosine Functions 𝒇 (𝒙)𝒐𝒓 𝒚=𝒂 𝒔𝒊𝒏(𝒃 𝒙 −𝒄)+𝒅 One comment on “Phase Shift” of the function Sometimes is located inside the parentheses. This will affect the value for the Phase Shift of the function. To find the actual Phase Shift of the function, you have to move the outside of the parentheses and adjust the value of “c” inside the parentheses. This adjusted value will provide the correct value for the Phase Shift of the function. 𝒇 ( 𝒙) 𝒐𝒓 𝒚=𝒂 𝒔𝒊𝒏 𝒃(𝒙 − 𝒄 𝒃 )+𝒅 This is normally the Phase Shift value when “b” is outside the parentheses in the original function. Phase Shift is 𝒃 𝒃 𝒃