WebGraphing.com Forum - View Thread

Welcome Guest | Login

WebGraphing.com Forum » List all forums » Forum: General Discussions » Thread: PRECAL HELP!!!

Thread Status: Normal
Total posts in this thread: 2

[Add To My Favorites] [Watch this Thread] [Post new Thread]

Author

This topic has been viewed 1787 times and has 1 reply

midyearnc

Joined: Jun 5, 2006
Posts: 16
Status: Offline

PRECAL HELP!!!

Reply to this Post
Reply with Quote

This question has me stumped. If anyone can help me solve it I would appreciate it.

The rectangular coordinates of a point are (1, -1). Find two pairs of polar coordinates (r, 0) for each point, one with r>0 and the other with r<0 . Express in radians.

PLEASE HELP!!!!!

[Jun 5, 2006 5:03:06 PM]

[Link]

pskinner

Joined: Apr 2, 2005
Posts: 797
Status: Offline

Re: PRECAL HELP!!!

Reply to this Post
Reply with Quote

This is a trig question.

The point (1,-1), connected to (0,0), makes an angle with the x-axis of -pi/4.

Drop a perpendicular from (1,-1) to the x-axis and draw the triangle in in the fourth quadrant. Now, you can compute r=sqrt(2)/2, using pythagoras. So, one point in polar coordinates is:

(sqrt(2)/2,-pi/4).

That's when r is positive. If r is negative with the same angle, the point gets rotated 180 degrees around the origin, so to get it back the angle needs to be 180 degrees in the other direction, so the other point is:

(-sqrt(2)/2,3pi/4)
----------------------------------------
Principal Skinner

[Jun 5, 2006 8:31:09 PM]

[Link]

[Show Thread Printable Version] [Post new Thread]