8.3 - Trigonometry

8.3 - Trigonometry

By Steve Dull

Objective

​To use the sine, cosine, and tangent ratios to determine side lengths and angle measures in right triangles.

What is trigonometry?

​The study of triangle measure

Work with a partner to complete exercise #1:

Multiple Choice

Determine $$\sin\ W$$   in this image

• $$\frac{12}{9}$$  

• $$\frac{9}{12}$$  

• $$\frac{4}{5}$$  

• $$\frac{12}{15}$$  

Complete the rest of #2

​(Take about 2 minutes)

That's great, Mr. Dull

​I mean, fun to do at parties, but...

What can we do with it?

Some text here about the topic of discussion

In this triangle we know one angle measure (two if we count the right angle) and one side length.

​

Using the trigonometric ratios, we can find the other side lengths. (And we'll find out next time we can find a missing angle too.​

​

​Some text here about the topic of discussion.

First, a status check

​Open your calculator and turn it landscape to open the scientific calculator.

Some text here about the topic of discussion

Be sure you see "Rad" on the button in the lower left hand corner. Find the keys that say "sin", "cos", and "tan".

​

We know something about the side opposite the 28 degree angle (it's labeled x) and we know the hypotenuse (19). So which trig ratio uses opposite and hypotenuse?

​

​Some text here about the topic of discussion.

Let's set it up:

Now put that in your calculator

​What'd you get?

Your turn

Open Ended

Determine the value of x

Let's try #12

Independent practice time :)