We have a right triangle and two of its sides: one leg and the hypotenuse. In order to find the remaining side we can use the pythagorean theorem. For a right triangle with legs a and b and hypotenuse c we have:
Using this in our question we get:
So the equation to be used to find the missing length is:
In order to find x we can square both sides of that equation:
Then we substract 25 from both sides:
And we apply a square root to both sides:
And that's the value of x.