Precalc help again! :(

[soulesschild]

Once again I have come to see the help of the great OT forum in my precalc adventures ><.

1. The point (- (root 21))/5 , 2/5 ) is the endpoint of arc s on the unit circle. Find the coordinates of the endpoint of the arc pi + s.

I don't get what the question means at all, second problem is the same thing.

2. The point (2/3 , - (root 5) ) is the endpoint of arc s on the unit circle. Find the coordinates of the endpoint of the arc pi - s

Note, these two problems arent related as in same circle, etc, just similar problem.

3. Write the following expression in u:

sin (inverse cosine 3/ (root 4u^2 +9) (assuming u > 0)

How in the world do i do that?

And last question is that, can anyone give me information about the graphs of sine/cosine and how to calculate amplitude, period, vertical translation and phase shift?

Example: y = -2 + 1/3 sin (1/4x)

For this i got the amplitude to be 1/3, period 8pi??, and vertical translation -2, and no phase shift, am i correct?

[psyadam]

Instead of attempting to answer that problem, which I probably couldn't do anyway, I'll just give you some moral support. Keep going at it! Fortunately for me, I only have had to take a year of pre-calc in my life-time (in hs) and that year second semester I believe I got a D. Fortunately a D is a passing grade in hs. You'll never have to take that class again, and while the class is called "Pre-Calc" it is the most horrible and most irrelevant class ever. The only good thing you might learn in that class are some interesting geometry theorems about triangles and more importantly matrices (which linear algebra is all about). Oh, and pre-calc has nothing to do with calculus.

edit:



Example: y = -2 + 1/3 sin (1/4x)

For this i got the amplitude to be 1/3, period 8pi??, and vertical translation -2, and no phase shift, am i correct?

Yes, that is all correct.



3. Write the following expression in u:

sin (inverse cosine 3/ (root 4u^2 +9) (assuming u > 0)

did you forget to say = 0? This makes no sense.



1. The point (- (root 21))/5 , 2/5 ) is the endpoint of arc s on the unit circle. Find the coordinates of the endpoint of the arc pi + s.

I don't get what the question means at all, second problem is the same thing.

2. The point (2/3 , - (root 5) ) is the endpoint of arc s on the unit circle. Find the coordinates of the endpoint of the arc pi - s?

I realized that this problem was extremely simple so I'll tell you the answer.

answer 1. : (-2/5 , (root 21))/5 )

answer 2. : (root 5 , - 2/3 )

[soulesschild]

for problem 2, thats jsut how it is, i dotn get it o.O

for 1 and 2, how did u arrive at that answer o.O

[psyadam]

Once again I have come to see the help of the great OT forum in my precalc adventures ><.

1. The point (- (root 21))/5 , 2/5 ) is the endpoint of arc s on the unit circle. Find the coordinates of the endpoint of the arc pi + s.

I don't get what the question means at all, second problem is the same thing.

2. The point (2/3 , - (root 5) ) is the endpoint of arc s on the unit circle. Find the coordinates of the endpoint of the arc pi - s



edit:

I realized that this problem was extremely simple so I'll tell you the answer.

answer 1. : (-2/5 , (root 21))/5 )

answer 2. : (root 5 , - 2/3 )

For #1 pi + s is going to be the point on the other side of the circle, so therefore if it's the unit circle (the circle with radius 1 centered at the origin), the coordainates of this point are just going to be found by swapping the coordainates and making both coordainates negative. Same idea for #2, although I could be wrong on this since it's pi - s instead of s - pi.