Question

Two sides of a right angle triangle is 5 inches each. how long is the third side

Answer 1

You can use Pythagorean theorem or trigonometry 
since two sides are 5, then this is an isosceles right triang
the other side must be the hypethenus
so we can use trig functions
any will do
sin(45) = 5/x   call third side x the missing one 
45 because that's the measure  angle of right angled isosceles (besides the right angle itself)
Ok so now you need to know what is sin(45) depends if you remember this special angle
sin(45) = root(2)/2
then we root(2)/2 = 5/x
solve for x
x = 10/root(2) = 5 root(2)
Perhaps Pythagorean theorem is easier to use, it's up to you
but here how you can start name the missing side x
remember the Pythagorean theorem is as follows 
a^2+b^2 = c^2 for any right triangle whose sides are a,b,c 
in this case a=5 and b=5
so we have 25+25 = x^2
solve for x again, you can continue this one

Answer 2

A= leg/side one= 5
b= leg/side two= 5
c= hypotenuse/side three


Use the Pythagorean Theorem
a^2 + b^2= c^2

5^2 + 5^2= c^2
square each 5

25 + 25= c^2

50= c^2
take square root of both sides

7.07 inches= c


ANSWER: The hypotenuse/third side is 7.07 inches.

Hope this helps! :)