SOLUTION: Identify the type of graph of the following polar equations. How can the graphs best be described? a. rsinθ = -11 https://www.dropbox.com/s/xo8bahbd0r5qxfh/Screen%20Sho

Algebra ->  Trigonometry-basics -> SOLUTION: Identify the type of graph of the following polar equations. How can the graphs best be described? a. rsinθ = -11 https://www.dropbox.com/s/xo8bahbd0r5qxfh/Screen%20Sho      Log On


   



Question 1102814: Identify the type of graph of the following polar equations. How can the graphs best be described?
a. rsinθ = -11
https://www.dropbox.com/s/xo8bahbd0r5qxfh/Screen%20Shot%202017-11-21%20at%209.18.13%20AM.png?dl=0
b. r = 3-2sinθ
https://www.dropbox.com/s/i99qmpa4vmrir0u/Screen%20Shot%202017-11-21%20at%209.18.23%20AM.png?dl=0
c. r^2 = 25cos2θ
https://www.dropbox.com/s/vboagd17yavux3s/Screen%20Shot%202017-11-21%20at%209.18.36%20AM.png?dl=0

Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
c . You probably asked question 1102813,
and from that question you should know that the answer to part c is
a lemniscate symmetric about the origin and the x- and y-axes,
or as your answer option says, in polar coordinates,
"symmetric about the pole and the lines theta=0 and the vertical line theta=pi%2F2 ."

a. As y=r%2Asin%28theta%29 is part of the conversion from polar to cartesian coordinates,
r%2Asin%28theta%29=-11 translates into y=-11 ,
and represents a horizontal line.

b. r=3-2sin%28theta%29 graphs ans a limacon with a dimple,
because, in absolute value, the coefficient of the trigonometric function (2)
is between 1/2 and 1 times the other term (3).
The dimple is at theta=pi%2F2 because that is where r is minimum.
For theta=pi%2F6 , r=3-2%2Asin%28pi%2F6%29=3%2A2%2A%281%2F2%29=3-1=2 and y=r%2Asin%28pi%2F6%29=2%2A%281%2F2%29=1 .
For theta=pi%2F4 , r=3-2%2Asin%28pi%2F4%29=3%2A2%2A%28sqrt%282%29%2F2%29=3-sqrt%282%29 and y has increased to ,
but as we keep approaching theta=pi%2F2 , y starts to decrease forming a dimple.
At theta=pi%2F2 , r=3-2%2Asin%28pi%2F2%29=3%2A2%2A1=3-2=1 and y=r%2Asin%28pi%2F2%29=1%2A1=1 again.