Week 9 - Introduction to Trigonometry

Must Know

• Calculate the missing sides of Right-Angled Triangles using Trigonometry

Could Know

• Calculate missing interior angles of Right-Angled Triangles using Trigonometry

Labeling right-angled triangles

There are three sides to a right-angled triangle: we give them all special names. From the last section we found that the longest side is called the hypotenuse. The hypotenuse is always opposite the right angle.

The other two sides are called the opposite and adjacent sides. Watch the video to see how these are labeled.

SOH CAH TOA

There are three buttons on your calculator you probably haven't used before: sin, cos, and tan. This video explains what each of these buttons do, which ones to use - and most importantly - what SOH CAH TOA means!

Your turn - SOH CAH TOA

Have a go at this worksheet on labeling the sides of a triangle and figuring out whether to use sin, cos or tan. Complete the exercises in your book and check your work with the answers on the last page.

Your turn - calculating side lengths

Complete this worksheet in your book and check your work with the answers on the last page. Remember that if you get stuck you can watch the video again or ask your teacher for help.

(For more practice, check out Beta Textbook page 277-279 and 281-282)