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Published byAngel Klein Modified over 2 years ago

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Determining signs of Trig Functions (Pos/Neg) x y Last class we found trig values using an x-y coordinate. Not all trig values are positive We can determine the signs of trig values based on the quadrant that the terminal side of the angle falls in The signs of the x and y coordinates factor into the signs of the trig values x + y + x - y + x - y - x + y -

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Finding Trig Values from an x-y coordinate x y Find the 6 trig functions for an angle which has terminal side passing through (-3, 4) and give them the proper signs This comes from the y coordinate which is positive

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Finding Trig Values from an x-y coordinate x y Find the 6 trig functions for an angle which has terminal side passing through (-3, 4) and give them the proper signs The hypotenuse is always positive So we have positive over positive meaning the sine is positive in the 2 nd quadrant

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Finding Trig Values from an x-y coordinate x y Find the 6 trig functions for an angle which has terminal side passing through (-3, 4) and give them the proper signs This is comes from the x-coordinate which is negative

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Finding Trig Values from an x-y coordinate x y Find the 6 trig functions for an angle which has terminal side passing through (-3, 4) and give them the proper signs Hypotenuse – always positive Negative over positive making cosine negative in the 2 nd quadrant

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Finding Trig Values from an x-y coordinate x y Find the 6 trig functions for an angle which has terminal side passing through (-3, 4) and give them the proper signs y-coordinate - positive x-coordinate - negative positive over negative means tan is negative in the 2 nd quadrant

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Finding Trig Values from an x-y coordinate x y Find the 6 trig functions for an angle which has terminal side passing through (-3, 4) and give them the proper signs csc has the same sign as sin, sec is the same as cos, cot is the same as tan

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Determining signs of Trig Functions (Pos/Neg) x y Add this into the original chart we started with x + y + x - y + x - y - x + y - sin + cos - tan - csc + sec - cot - sin + cos + tan + csc + sec + cot + sin - cos - tan + csc - sec - cot + sin - cos + tan - csc - sec + cot -

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Finding Trig Values from an x-y coordinate x y Find the 6 trig functions for an angle which has terminal side passing through (2, -7) and give them the proper signs

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Finding Trig Values from an x-y coordinate x y Find the 6 trig functions for an angle which has terminal side passing through (-5, 3) and give them the proper signs

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Homework – pg 697 #9, 13, 14, 17, 20

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