I am training Trigonometry just for fun, so I am not in a hurry, but would like to know how to answer this question - not the result, but how to do it. Sorry because I understand this is too basic for you, but I forgot almost everything from elementary school...
A sheet of paper measures $210 \space mm \times 297 \space mm$. Consider a diagonal from one corner of the sheet to its opposite corner, and choose a point on the diagonal so that its distance to the furthest edge of the sheet is equal to the length of that edge, that is, $210 \space mm$. What is the distance of the point to the nearest edge of the sheet?
This is the point I reached (did it in Paint - sorry about the quality):
So as you can see I tried but with no success, and would like to know how to continue. Someone can help me?
Thank you very much in advance.