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)
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.
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