SOLUTION: cscx=2, 0<x<2pie

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Question 822990: cscx=2, 0
Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
csc%28x%29=2
Since some students don't learn the special angle values for sec, csc and cot, I am going to use the fact that csc and sin are reciprocals of each other to rewrite the equation in terms of sin(x). (If you already know what reference angle has a csc of 2, the following steps are unnecessary.)
1%2Fsin%28x%29+=+2
Multiply by sin(x):
1+=+2sin%28x%29
Divide by 2:
1%2F2+=+sin%28x%29

We should recognize that 1/2 (positive or negative) is a special angle value for sin. Without our calculator we should know that a 1/2 for sin indicates a reference angle of pi%2F3. Since the 1/2 is positive and since sin is negative in the 1st and 2nd quadrants we should get the following general solution equations:
x+=+pi%2F3%2B2pi%2An (for the 1st quadrant)
x+=+pi-pi%2F3%2B2pi%2An (for the 2nd quadrant)
The second equation simplifies:
x+=+pi%2F3%2B2pi%2An
x+=+2pi%2F3%2B2pi%2An

Now we try various integer values for n as we search for specific solutions which are in the specified interval.
From x+=+pi%2F3%2B2pi%2An:
If n = 0 then x+=+pi%2F3
If n = 1 (or larger) then x is too large for the interval
If n = -1 (or smaller) then theta is too small for the interval
From x+=+2pi%2F3%2B2pi%2An:
If n = 0 then x+=+2pi%2F3
If n = 1 (or larger) then x is too large for the interval
If n = -1 (or smaller) then x is too small for the interval

So the only solutions in the specified interval are: pi%2F3 and 2pi%2F3.