We can find out what LM is based on the fact that the bases of the 2 triangles are the same, this would also mean that the hypotenuse sides of the triangles should also be the same as well. Thus the sides of LM should also equal the sides of MN.
Another way, is to assume that the triangles are right angle ones, and use Pythagorean theorem to solve for the height and use that to solve for the hypotenuse.
The easiest way to tell if a number is rational or not is to attempt to express it as a fraction. If you can, then the number is rational. If not, then the number is irrational. All integers are rational numbers, because they can be written as a fraction (for example, the integer 8 = 8/1). But numbers like pi or sqrt(2) cannot be written as a fraction and are not rational.
say, you have half a pie, and 2 sisters, if you divide the half-pie in 3 equal pieces, how much is everyone getting of the whole pie? well, is the quotient of 1/2 and 3.
