Question 60432
If we assume that a right triangle has three sides, one being the hypotenuse, then this problem will have two possible solutions and we will do them both. We will apply the Pythagorean Theorem which states that in a right triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides.
Let x be the missing side and lets assume that it's the hypotenuse. Thus, we have to solve the following equation:
x^2=35^2+28^2 =1225+784=2009
therefore x=sqrt(2009)=44.8 feet

Now lets assume that it's not the hypotenuse.  If it's not, then 35 must be and, by inspection, we know this has to be a 3 4 5 triangle but we'll solve it anyway. 
Now we have to solve the following equation:
35^2=x^2+28^2 or
x^2=35^2-28^2=1225-784=441
therefore x=sqrt(441)=21 feet

Hope this helps-----ptaylor