i was just wondering how to find corresponding values from the first quadrants since you said this is necessary before computing, on your website you gave an example:
11B/6 from QIII = B/6 in QI
but how do you know this is the corresponding value? Is there some kind of conversion or just purely memorization?
I take it you haven't studied Trig yet, so I will try to explain it in such a way that it's understandable. So here goes. It is easier to think in degrees instead of radians, so the values I use here will be in degrees.
If you look on the graph I drew where it shows the layout of the different quadrants, you will see that each section has an equal range of Pi/2 or 90 degrees. For QI the values can be from 0<=x<90, for QII the values are from 90<=x<180, for QIII the values are from 180<=x<270, and QIV the values are from 270<=x<360 (or 0). Notice 360 degrees is the same thing as 0 degrees.
So the question is how do you find the corresponding values? What you do is find the angle from the given value to the x-axis. Let's see if I can explain this better using examples:
Ex [1] If I had an angle of 150 degrees (which is in QII), the corresponding angle in QI is ___?
Remember we are working from the x-axis.
Since we are in QII, the x-axis represents the value 180.
The question is, what angle is made from 150 degrees to the x-axis (which is represented by 180 degrees)?
The answer is 30 degrees. Simply subtract 180 - 150 for the answer. So the corresponding angle in QI is 30 degrees.
Ex [2] If I had an angle of 225 degrees (which is in QIII), the corresponding angle in QI is ___?
We are always using the x-axis, which is represented by 180 degrees in this example.
What angle is made from 225 degrees to the x-axis.
The answer is 45 degrees. Simply subtract 225 - 180 for the answer. So the corresponding angle in QI is 45 degrees.
Ex [3] If I had an angle of 300 degrees (which is in QIV), the corresponding angle is QI is ___?
This time we are in QIV so the x-axis is represented by 360 degrees. (It is easier to use this values instead of 0, so we don't end up with a negative number.)
What is the angle made from the x-axis to 300 degrees?
The answer is 60 degrees. Simply subtract 360 - 300 for the answer. So the corresponding value in QI is 60 degrees.
It gets a little harder when dealing with radians as you have to think in terms of Pi. So I would always convert to degrees before working this problem. You might find that helpful.
Also, sometimes the question will give you an angle that is more than 360 degrees or less than 0 degrees. On problems like this you can subtract or add 360 degrees until the value is somewhere between 0 and 360.
Let me know if I need to explain differently.
Webmaster
P.S. I assume since you used the value B to represent Pi that is what you saw on the website. I had to change the font so I could use the character "Pi". If you do not have this font installed, I guess you see the value B. I am sorry about this, would it help if I changed the sign to Pi instead of the symbol for Pi?
Thanks, i now feel alot more comfortable with it now. You are right, i haven't had much trig yet other than sin cos, and tan; which i learned in Geometry last year, i think things would be alot better after this summer when i take pre-calc, i wanted to take that over the summer but they only offered regular pre-calc, not pre-ap. As for the font part, i think it is ok to leave it like that, although it took me about 3 second to figure out that was Pi. Also, i am doing both calculator and numbersense this year, and currently i am having trouble on how to solve some of the word problems on the test, i don't know if it is ok to ask you questions about it since this is a numbersense forum, should i email you the problems or just post it here?
