Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I'm having a hard time trying to wrap my head around this problem.

Imagine a line of length $A+B$ with center $C$, with a circle with $d = A+B$ with center at $C$.
Now imagine drawing a line at $90^{\circ}$ from an arbitrary point, $D$, along the line $A+B$, which intersects the circle at point $E$.
How could one calculate the distance between $D$ and $E$ the point?

This is kinda hard to explain, as English is not my first language, so please refer to picture for an example.

Explanatory image

Feel free to help me tag this appropriately.

share|cite|improve this question
    
You are looking for $ED$? – S. Snape Aug 4 '13 at 22:51
    
@BabakS. Yes, the distance between those two points. – JohnWO Aug 5 '13 at 11:19
up vote 1 down vote accepted

Pithagora's theorem tells you that $$CD^2+DE^2 = \left(\frac{AB}{2}\right)^2$$

share|cite|improve this answer
    
We can also assume that $CD$ is 2 on this diagram and that $CE=\frac{AB}2=CB=AC$ – Ali Caglayan Aug 4 '13 at 22:57
1  
Sweet... Thanks for reminding me of this fundamental theorem! (It has been a VERY long while since I dabbled with geometry... Not since grade school, if I recall correctly...) This is what I ended up with: $DE = \sqrt{\left (\frac{AB}{2}\right )^2-CD^2}$. Again, thanks! – JohnWO Aug 5 '13 at 11:33

there is this possibility too.

BD/DE=DE/AD

and DE²=BD*DA

share|cite|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.