1. 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.

2. Section 1.3 Trigonometric Functions
Objective:
SWBAT use trigonometric functions with quadrantal angles.

3. 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?

4. FINDING FUNCTION VALUES OF QUADRANTAL ANGLES
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. FINDING FUNCTION VALUES OF QUADRANTAL ANGLES
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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6. 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.

7. Commonly Used Function Values
sin 
cos 
tan 
cot 
sec 
csc  0 1
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90
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180 1
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270
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360

8. 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.

9. Caution
One of the most common errors involving calculators in trigonometry occurs when the calculator is set for radian measure, rather than degree measure.

10. Homework:
Page 25 #’s (evens)