• Welcome! The new FreeMathHelp.com forum is live. We've moved from VB4 to Xenforo 2.1 as our underlying software. Hopefully you find the upgrade to be a positive change. Please feel free to reach out as issues arise -- things will be a little different, and minor issues will no doubt crop up.

Complex Related Rates: Points A and B move along the x- and y- axes, respectively,...

harveyandstanley

New member
Joined
Apr 15, 2016
Messages
1
Points A and B move along the x- and y- axes, respectively, in such a way that the perpendicular distance r from the origin to AB remains constant. How fast is OA changing and is it increasing or decreasing when OB=2r and B is moving toward o at the rate of 0.3r m/sec?
 

Subhotosh Khan

Super Moderator
Staff member
Joined
Jun 18, 2007
Messages
18,086
Points A and B move along the x- and y- axes, respectively, in such a way that the perpendicular distance r from the origin to AB remains constant. How fast is OA changing and is it increasing or decreasing when OB=2r and B is moving toward o at the rate of 0.3r m/sec?
What are your thoughts?

Please share your work with us ...even if you know it is wrong

If you are stuck at the beginning tell us and we'll start with the definitions.

You need to read the rules of this forum. Please read the post titled "Read before Posting" at the following URL:

http://www.freemathhelp.com/forum/th...Before-Posting
 

stapel

Super Moderator
Staff member
Joined
Feb 4, 2004
Messages
15,937
Points A and B move along the x- and y-axes, respectively, in such a way that the perpendicular distance r from the origin to AB remains constant. How fast is OA changing...
Which point is "O"? Does this mean "the origin"?

...and is it increasing or decreasing when OB=2r and B is moving toward o...
Does "o" mean "O", or is it a different point?

...at the rate of 0.3r m/sec?
Is the "r" supposed to be in the "rate" expression?

When you reply, please include a clear listing of your thoughts and efforts so far, starting with a scan of (or detailed description of) your initial drawing for this exercise. Thank you! ;)
 

Subhotosh Khan

Super Moderator
Staff member
Joined
Jun 18, 2007
Messages
18,086
Points A and B move along the x- and y- axes, respectively, in such a way that the perpendicular distance r from the origin to AB remains constant. How fast is OA changing and is it increasing or decreasing when OB=2r and B is moving toward o at the rate of 0.3r m/sec?
Let the co-ordinate of the point A be[x[SUB]A[/SUB],0] and the co-ordinate of the point B be [0,y[SUB]B[/SUB]].

What is the equation of the line joining A and B?

What is the length of the perpendicular distance of a given point (here (0,0] to a given line (here AB)?
 
Top