Warm Up
Find the values of the six trigonometric functions for 300
Section 2.3
Finding Trigonometric Function Values Using a Calculator
Objective:
SWBAT find trig function values using a calculator.
Function Values Using a Calculator
• Calculators are capable of finding trigonometric
function values.
• When evaluating trigonometric functions of angles
given in degrees, remember that the calculator must
be set in degree mode.
• Remember that most calculator values of
trigonometric functions are approximations.
Finding Function Values with a Calculator
Approximate the value of each expression.
• a) sin 38 24
24
 38.4
60
sin 38 24  sin 38.4
38 24  38
 .6211477
• b) cot 68.4832 
• Use the identity
1
cot  
.
tan 
• cot 68.4832 
 .3942492
FINDING FUNCTION VALUES WITH A CALCULATOR
• Approximate the value of each expression.
(a) sin 49°12′
≈ .75699506
(b) sec 97.977°
Calculators do not have a secant
key, so first find cos 97.977° and
then take the reciprocal.
sec 97.977° ≈ –.75699506
FINDING FUNCTION VALUES WITH A CALCULATOR
• Approximate the value of each expression.
(c)
Use the reciprocal identity
(d) sin (–246°) ≈ –.91354546
Angle Measures Using a Calculator
REMEMBER:
• Graphing calculators have three inverse
functions.
sin
1
1
-1
or
tan
x
x,cos x,
• If x is an appropriate number, then
gives the measure of an angle whose
sine, cosine, or tangent is x.
Using Inverse Trigonometric Functions to
Find Angles
•
Use a calculator to find an angle  in the
interval [0 ,90 ] that satisfies each condition.
• sin   .8535508
Using the degree mode and the inverse sine
function, we find that an angle having sine
value .8535508 is 58.6 .
1
sin
.8535508  58.6
We write the result as
Using Inverse Trigonometric Functions
to Find Angles continued
• sec  2.486879
1
Use the identity cos   sec  . Find the
reciprocal of 2.48679 to get cos  .4021104.
Now find  using the inverse cosine function.
The result is   66.289824
USING INVERSE TRIGONOMETRIC FUNCTIONS TO FIND
ANGLES
• Use a calculator to find an angle θ in the
interval [0°, 90°] that satisfies each condition.
(a)
Use degree mode and the
inverse sine function.
(b)
Use the identity
Homework
• Page 64
• # 5-28 evens