Inverse Trigonometric Lesson

Inverse Trig

By Deb Scott

Objective: Find missing angle measurement using Trig

Trig so far...

Inverse Trig Ratios

We use inverse trig functions to find angle measures.

(You will need a calculator)

What if we want to solve for an angle?

Then we need to use inverse functions

How do we use Trig Functions to find missing angles?

• Step 1: Identify the angle

• Step 2: Label opp, adj, and hyp based on given angle

• Step 3: Identify the appropriate trig function to solve for the missing angle

• Step 4: Use sin^-1 , cos^-1 , tan^-1 to solve the equation for the angle 

Multiple Choice

Set up an equation that could be used to solve for the variable.

Multiple Choice

Set up an equation that could be used to solve for the variable.

Multiple Choice

Which equation is true?

• sin (x) = 14/29

• cos (x) = 14/29

• tan (x) = 14/29

• tan (x) = 29/14

Multiple Choice

Which equation would you use to solve for the unknown angle?

• x = sin^–1(4/5)

• x = cos^–1(4/5)

• x = cos^–1(5/4)

• x = tan^–1(4/5)

Multiple Choice

Choose the correct ratio.

• sin^-1(9/20)

• cos^-1(9/20)

• tan^-1(9/20)

• cos^-1(20/9)

Multiple Choice

Which equation could be used to solve for the unknown angle?

• x =sin^–1(25/24)

• x = sin^–1(24/25)

• x = sin^–1(25/7)

• x = sin^–1(7/25)

Multiple Choice

Find the measure of the angle. Round to the nearest tenth.

• 30.8

• 32.1

• 34.3

• 36.9

Multiple Choice

Find the measure of angle A.

• 24

• 90

• 66

• 42

Multiple Choice

Find the measure of the missing angle.

• 64^o

• 26^o

• 61^o

• 8^o

Multiple Choice

When do you use an inverse trig function?

• When you are finding a missing side.

• When you are finding a missing angle.

• You can use it anytime.

Multiple Choice

Find the measure of the indicated angle (?) round to the nearest tenth.

• 9.4
• 55.2
• 20.15
• 19.4

Multiple Choice

Use inverse trig ratios (SOH CAH TOA) to solve for the missing angle

• 32°
• 44°
• 61°
• 50°

Multiple Choice

Use inverse trig ratios (SOH CAH TOA) to solve for the missing angle

• 33°
• 49°
• 39°
• 41°

Multiple Choice

Find the measure of the missing angle.

• 49^o
• 50^o
• 41^o
• 33^o

Multiple Choice

Use the appropriate trig ratio to find the measure of the missing angle. Round to the nearest 10th.

• 9.4 degrees

• 55.2 degrees

• 20.2 degrees

• 19.4 degrees

Multiple Choice

Which equation is true?

• sin (x) = 11/27

• sin (x) = 27/11

• cos (x) = 11/27

• tan (x) = 11/27

Multiple Choice

Use the appropriate trig ratio to find the measure of the missing angle. Round to the nearest 10th.

• 64^o

• 26^o

• 61^o

• .008^o

Multiple Choice

Solve for m∠S.

• 21
• 69
• 23
• 67

Multiple Choice

Find the measure of the indicated angle.

• 9.39
• 55.2
• 20.2
• 19.4

Multiple Choice

Which equation would you use to solve for the unknown angle?

• x = tan^–1(24/7)

• x = tan^–1(7/24)

• x = tan^–1(25/7)

• x = tan^–1(7/25)

Multiple Choice

Find the measure of the missing angle.

• 64^o

• 26^o

• 61^o

• .008^o

Multiple Choice

Find the degree measure of the indicated angle.

• 34.8

• 39.4

• 55.2

• 58.6

Multiple Choice

Find the degree measure of the missing angle.

• 15.8^o

• 25.8^o

• 28.9^o

• 61.1^o

Multiple Choice

Solve for the missing angle in degrees

• 36.9

• 42.4

• 48.6

• 53.1

Fill in the Blanks