# Determining signs of Trig Functions (Pos/Neg)

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

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

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

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

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

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

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

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

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

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

Homework – pg 697 #9, 13, 14, 17, 20

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