# Can I find the distance? I know $D$, $\alpha$ and $\theta$. I also know the $a/b$ ratio of $k$. I don't know $c$. Can I find out $a$ or $b$ or $a+b$?

• It would have been good style to mention this directly related question: math.stackexchange.com/questions/59636/can-i-find-the-angle/… to avoid unnecessary duplication of efforts. – joriki Aug 25 '11 at 8:04
• sorry this is a different question.. they may look similar but nothing is far from truth.. – Frank Aug 25 '11 at 8:25
• I can see it's a different question; otherwise I would have voted to close it as a duplicate. Nevertheless it's clear that some insight might be gained from answers to the other question, and there's no reason not to include a link. – joriki Aug 25 '11 at 8:30
• What is $\alpha$? An angle? – Peter Taylor Aug 25 '11 at 8:57
• α is the angle.. Sorry it wasn't clear. – Frank Aug 25 '11 at 9:03

This is a slightly different question to this one. But the answer is the same: it is not possible to determine $a$ or $b$ or $a+b$. Look at this figure: We can move the red lines anywhere in the $\theta$ cone without changing $\alpha$ and $k=a/b$. But $a$ and $b$ are changed.