Download Section 1.3 Day 2

Do Now
The terminal side of angle θ in standard position passes through
the point (12, 16). Find the value of the six trigonometric
functions of angle θ.
Section 1.3
Trigonometric Functions
Objective:
SWBAT use trigonometric functions
with quadrantal angles.
Quadrantal Angles
Quadrantal Angle: An angle whose terminal side
is on an axis.
Think about x or y equaling 0. What would happen to
the value of r in your trigonometric functions?
Example 1
FINDING FUNCTION VALUES OF
QUADRANTAL ANGLES
Find the values of the six trigonometric functions for an
angle of 90°.
The terminal side passes
through (0, 1). So x = 0, y = 1,
and r = 1.
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5.2-4
Example 2
FINDING FUNCTION VALUES OF
QUADRANTAL ANGLES
Find the values of the six
trigonometric functions for an
angle θ in standard position with
terminal side through
(–3, 0).
x = –3, y = 0, and r = 3.
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Undefined Function Values
• If the terminal side of a quadrantal angle lies
along the y-axis, then the tangent and secant
functions are undefined.
• If the terminal side of a quadrantal angle lies
along the x-axis, then the cotangent and
cosecant functions are undefined.
Commonly Used Function Values

sin 
cos 
tan 
cot 
sec 
csc 
0
0
1
0
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1
undefined
90
1
0
undefined
0
undefined
1
180
0
1
0
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1
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270
1
0
undefined
0
undefined
1
360
0
1
0
undefined
1
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Using a Calculator
• A calculator in degree
mode returns the correct
values for sin 90° and cos
90°.
• The second screen shows
an ERROR message for tan
90° because 90° is not in
the domain of the tangent
function.
Caution
One of the most common errors involving
calculators in trigonometry occurs when
the calculator is set for radian measure,
rather than degree measure.
Homework:
Page 25 #’s 34-42 (evens)