We mainly focused on how we use calculators today. To do this trigonometry we need to be using scientific calculators. These are basically any calculator that has a "sin" "cos" and "tan" button. While a lot of phones do now have these on their calculators, it is a lot easier and a lot safer to use a proper calculator.
When we first turn our calculator on we have to make sure it is in degrees mode. Since each calculator is slightly different, I suggest you look for instructions for your specific calculator as to how to do this. If you are having troubles, leave a comment or come and see me and I will try and work it out with you.
Once our calculator is in degrees mode, we can then start working through problems. For example, we may be asked to find sin 43o
To do this, we have to grab our calculator and press the "sin" button. We then enter the number of degrees. For this example we will enter "43". Some calculators will try and put this in brackets for you, {i.e. your calculator will read out sin(43 }, which is fine. You just have to make sure that you close these brackets by pressing the " ) " button. Once we have entered this into our calculator, hit the equals button. If you have done this correctly, you should get 0.6819983601
You may also be asked to find something like 6.7 cos 31o
This is basically asking us to find "6.7 lots of cos 31 degrees". To do this, we grab our calculators and put in "6.7" then hit the "multiply" button. We then press the "cos" button and then type in "31". If you need to, make sure you close the brackets. Then hit equals. You should get 5.743020915
You may also be asked to find 43/tan 21o
To do this we want to grab the calculator again and put in "43" then press the "divide" button then hit "tan" then "21", again remembering to close your brackets if your calculator requires. Press equals and you should get 112.0188298
We also looked at finding unknowns in different trig problems. For example we may be able to find x in sin 37o = x/9
To do this we want to rearrange the equation to have x by itself on one side of the equals sign, then everything else on the other side. To do this we want to multiply each side by 9 (i.e. the number on the bottom of the fraction). This will effectively cancel the 9 from the right hand side, and we will be left with:
9 sin
37o = x
This leaves us with x by itself on one side of the equals sign and everything else on the other side so we can now just use our calculator to solve it. We can then easily solve for x by sticking the part on the left hand side into our calculator in the same way we did in the examples above. We will then get x = 5.416335208
Similar to this, we may also be asked to find cos
82o = 14/x
Again, same as before we want to rearrange this so the x in by itself on one side of the equals sign and everything else is on the other side. This question is slightly different to the one above. If we look at the fraction on the right hand side, we see the the number is on the top and the letter is on the bottom. This is the opposite to the previous example above, where the letter was on top and the number was on the bottom. This means when we rearrange the equation, we will pretty much do the opposite of what we did above. In the example above, we moved the 9 to the left hand side and multiplied it. For this example we will move the 14 to the left had side as well, except because we are doing the opposite we will divide it this time. So, we will be left with:
14/cos
82o = x
This leaves us with x by itself on one side of the equals sign and everything else on the other side so we can now just use our calculator to solve it. Again, we just put the part on the left hand side of the brackets into our calculator using the same technique as we did above. If we do this we should get x = 100.5941515
This should give you the skills to work through the next two problems on the worksheet. This worksheet can be found under the "Worksheets" tab at the top of the page. As always, feel free to comment on this post if you have any questions or concerns.
Also, if you do not have a scientific calculator as I mentioned above I would highly suggest you get one. You should be able to find one in Kmart or Officeworks or other places. I did find this one on eBay for a great price if you are happy to buy one online:
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