2)
) = cot(y))
To answer your question,
 )
is definately undefined. You just have to ask yourself what this question was asking. If indeed y =
or some multiple of it, then yes, it would be undefined. HOWEVER for any other value in the circle this is defined. If y =
It would be valid, and so on.
3)
 = sin(x)cos(y) + cos(x)sin(y))
Those we know sin(x). We have to work out the others given the info.
For the
)
case, draw a right angled triangle, with 4 as the opposite side, 5 as the hypotenuse. Then, you have a 3,4,5 triangle. Since it is in the 1st quadrant, cos(x),tan(x) anything you pick will be positive. Since we are dealing with the x variable, we want to find cos(x) so we can work out
)
From the triangle
 = adj/hyp = 3/5)
Simiarly with the "y" variable, we want to know cos(y) and sin(y) but are given tan(y). Note it is in the third quadrant, hence sin(y), cos(y) are going to be negative.
So drawing a right angled triangle again, tan(y) implies the opposite side = 5, adjacent side = 12, so we have a 5,12,13 triangle.
Thus sin(y) = -
 = -\frac{12}{13})
As per the
equation we plug and chug our answer in to obtain the solution.
4) you are correct. Create a right angled triangle in the second quadrant which has 30 degrees in it, hypotenuse 1.
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