Question 1198034
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Hey, there is no any need to memorize the signs of trigonometry functions in four quadrants.


Saying honestly, I think that it is impossible to memorize, if you do not understand the meaning of trigonometry functions,
and there is no need to memorize (no need to fill your mind by the stuff which you do not understand): it is bad way of teaching.


You need to imagine mentally the unit circle as a watch clock face.


The sine function sin(t) is vertical coordinate of the arrow's end: 
it is in positive domain in Q1 and Q2 and in negative domain in Q3 and Q4.


Similar for the cosine function cos(t): it is horizontal coordinate of the arrow's end,
and therefore it is positive in Q1 and Q4 and negative in Q2 and Q3.


As soon as you understand it, the way is open for you to move forward,
and your mind is free from the useless stuff.