9-1

This week I'm going to explain to you how to use sinx, cosx, and tanx to find side lengths of a triangle.

To remember how to do this you are going to use the word SOHCAHTOA. This is an easy way to remember the formulas to do this.

• Sinx=Opp/Hyp
• Cosx=Adj/Hyp
• Tanx=Opp/Adj

These formulas are only to be used of RIGHT triangles. Also, when finding these side lengths never use the 90 degree angle. Always use the other angle given.

Okay, so now I'm going to do an example.

Example 1: Find d and f

Okay, so we are going to find the side length f first.

Since you are give angle E, which is 12 degrees and you need to find f. You are going to use tanx=opp/adj. Which is going to give you tan12=9/f. When you solve for f you are going to get f=42.342 degrees.

Now we are going to find the side length d.

Your going to use angle E again, but this time you are going to use sinx=opp/hyp. This is going to give you sin12=9/d. When you solve for d you are going to get d=43.288 degrees.

So you answers are going to be f=42.342 degrees and d=43.288 degrees.

--Halie!