 This video is called right triangle trig 3 for the rest of the videos you can see on your note sheet There's six examples left these are very important examples to be able to not only set up but to solve correctly you're going to need a Calculator to do these at this point if you do not have a calculator you really won't have any way of getting these answers correct and Life in geometry class will become very difficult So pause this video now if you need to go find your calculator and make sure it is in the degree mode if you're not sure what a degree mode is make sure you ask your teacher about this in class tomorrow It's very very important many of you your calculators will already be in degree mode just because so hopefully as we go through these Questions when you punch practice punching things in your calculator It will work and you'll get the same numbers as I do if you don't that means your calculator is in the wrong mode Or it's kind of like it's in the wrong language and you'll need to figure out how to get it in the correct place And that will be a question for your teacher because I obviously can't reach through this video and help you So let's look at this first problem. We've got a right triangle and we want to solve for x. We're trying to Looks like x is a side length. We can use so katoa. I'm going to go ahead and Write that down. You should already have that on your note sheet somewhere on this side if you don't Make sure you get it there It looks like what you're going to do to solve for x is you're going to pick one of the triangle one of the angles To be your perspective don't pick the 90-degree angle to be your perspective So let's go ahead and pick the 26 now from the 26 X would be my opposite side where the 43 is opposite my right angle So that would be the hypotenuse so think about it which of my Trig ratios have opposite and hypotenuse as their fraction if you guessed sign You're starting to get the hang of it because the sign is the opposite over the hypotenuse So now we're going to finally do a problem and plug this in our calculator We have the sign of 26 degrees is the opposite which is x over the hypotenuse which is 43 Now the weird thing is is this is just an algebra problem It looks different and looks complicated because we've got this weird sign number in there But just please try to think about this is really just a number so to get x by itself We don't really have to do anything different to get x by itself. I want to get rid of that 43 So I'll multiply both sides by 43 Because remember to get rid of a fraction you take whatever is in the denominator and multiply both sides by it So you have 43 times the sign of 26 equals x So now what you have to do is this is really important is to practice punching things in your calculator To do 43 times the sign of 26. We are going to get x equals 18.9 if you don't get that that's definitely something that you need to practice with your teacher To make sure you get there all right So basically in your calculator do sign of 26 press equal then hit times 43 and press equal again now depending on your calculator the sign of 26 part will be different Depending on what calculator you have so if you're not figuring out how to get 18.9 as your answer when you plug things in your calculator Don't despair but get help if I could reach through the video and help you I promise I would Let's try another example if you had trouble in that last problem figuring out how to use your calculator Try again when you do this one if you're still not getting the same answers as me again Just ask your teacher tomorrow. She will help she or he will help you get The calculator usage part down but for this for kind of for this moment Just make sure that you're practicing setting things up correctly and worry about the calculator part later So in this problem to go from the perspective of the 60 I have 38 as my hypotenuse and x as my adjacent and so when you look at so katoha You can remember that cosine is adjacent over hypotenuse so The most important part of this problem is now setting things up correctly the cosine of 60 Equals x over 38. We're simply trying to get x alone So I've got to take what's in the denominator that 38 multiply by both sides So on the right hand side the 38s cancel so I have 38 times the cosine of 60 Equals x so at this step try to get the answer in your calculator the answer rounds to 19 And see if you can get there what you can try is punching in cosine of 60 press equal Do times 38 press equal again? Hopefully you get to 19 some of you to do this problem You have to do 60 then hit cosine press equal do times 38 and press equal again and see if you get 19 One little side note about this problem is that there's actually another way to solve this if you've noticed It's a 30 60 90 triangle. It's a special right triangle So you actually wouldn't even need your calculator or cosine to do this You could use your n and root 3 and 2 n if you preferred