College Math
posted by Carol .
Find the missing side. Approximate the answer to three decimal places when appropriate.
Possible answers are: (A) 10yd, (B)31.623yd, (C) 20yd, (D) 400yd. Can you help me? I have done this so far. 1801525=140. I have tried everything that I know of to get the answer but I'm ata loss. I have tried the examples for this question but I'm not coming up with anything.

You'd better describe the figure if you want some help.

This is a triangle with sides of A,B,C.
Side A = 15 yd and side C=25 yd. I need to find the missing side 
any side is less than the sum of the other two sides, so the missing side must be less than 40.
That eliminates (D)
Other than that, we need more information. Imagine you have two sticks of length 15 and 25. Connect one end of each together, into a V shape.
Now, you can imagine that you can wave the sticks about, making the 3rd side anything between 0 and 40 yd.
Still need one more piece of info, like an angle. If the angle between the two sides is a right angle, then the third side is √(15^2+25^2) = √850 = 29.15, so that's not it.
What else do you know? 
Oh, yeah. The 3rd side must be greater than 10, since 25 < 15+x. So (A) is out.
That leaves (B) and (C) as possibilities.