Taylor's 3rd blog

The following are the things that I learned from lesson 7.4.

This is how you will find a reference angle.

First, you need to figure out what quadrant the angle is in.

Next, you need to you will need to determine if the trig. function is a positive function or a negative function.

Then, you will subtract 180 degrees form the angle until you have an absolute value that is between 0 and 90 degrees.

Finally, if the angle is on the trig chart then plug it in and if it isn’t leave it alone or you can plug it into the calculator.

HINT: EVALUATE ATUALLY MEANS THAT YOU NEED TO FIND THE NUMBER ANSWER UNLESS OTHERWISE SPECIFIED BY THE INSTRUCTIONS.

Here are the angles that are on the trig chart.

0 degrees = 0
30 degrees = PI/6
45 degrees = PI/4
60 degrees = PI/3
90 degrees = PI/2

Now lets apply what we have learned.

Find the reference angle of sin 600 degrees

(SINCE I DON’T KNOW HOW TO PUT A GAPH ON THE COMPUTER I’LL JUST TELL YOU WHAT TO DO)

Ok first you will subtract 360 degrees from 600 degrees and you will get 240 degrees. Since it is 240 degrees it will be in the 3rd quadrant. This will also make sin negative because the y is negative in this quadrant.

600-180= 420-180= 240 - 180= 60 degrees
-sin 60 degrees

Then we need to subtract 180 degrees from 600 degrees until you get 60 degrees then you simply do what I just did and write it out.

60 degrees= PI/3
- Square Root of 3/ 2

Since 60 degrees is in your trig chart we will put down what sin PI/3 is in the trig chart. Also since sin is negative the answer is negative.

Lets try cos next.

Find the reference angle of cos 780 degrees.

Ok first you will subtract 360 degrees from 780 degrees twice and you will get 60 degrees. Since it is 60 degrees it will be in the 1st quadrant. This will also make cos positive because the x is positive in this quadrant.

780-180= 600 -180= 420 - 180= 240 -180= 60 degrees

cos 60 degrees

Then we need to subtract 180 degrees from 780 degrees until you get 60 degrees then you simply do what I just did and write it out.

60 degrees= PI/3
1/2

Since 60 degrees is in your trig chart we will put down what cos PI/3 is in the trig chart.

That is what I learned in lesson 7.4. Until next time!