SOLUTION: Can somebody please show how to find the reference angles for these values. The steps, not just the answe could be really helpful to so I can see how to solve thanks in advance.

Algebra ->  Trigonometry-basics -> SOLUTION: Can somebody please show how to find the reference angles for these values. The steps, not just the answe could be really helpful to so I can see how to solve thanks in advance.       Log On


   

Question 904033: Can somebody please show how to find the reference angles for these values. The steps, not just the answe could be really helpful to so I can see how to solve
thanks in advance.
a) -25pi/18
b)-7pi/9
c)-29pi/18
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
You can first convert each
angle to a positive angle
------------------------
A negative angle starts at +0%2Api+
and rotates CW
The whole circle is +2%2Api+=+%28+36%2F18%29%2Api+
-----------------
(a)
+%28+36%2F18+%29%2Api+-+%28+25%2F18+%29%2Api+=+%28+11%2F18+%29%2Api+
That would be the positive version of the angle
which is arrived at by rotating CCW from +0%2Api+
-----------------
Which quadrant is it in?
+%289%2F18+%29%2Api+ is 90 degrees
So, +%2811%2F18%29%2Api+ is +%282%2F18%29%2Api+
past 90 degrees ( 2nd quadrant )
------------------
That means it makes an angle of
+%287%2F18%29%2Api+ with the horizontal
-----------------------------
The components of this angle are:
+-cos%28+%287%2F18%29%2Api+%29+ ( x-coordinate )
+sin%28+%287%2F18%29+%2Api+%29+ ( y-coorinate )
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Hope this helps