Answer:
5

Explanation:
The triangle has 2 equal legs, name them x so
Using Pythagoras' identity
The square on the hypotenuse is equal to the sum of the squares on the other 2 sides, that is
x² + x² = 10²
2x² = 100 ( divide both sides by 2 )
x² = 50 ( take the square root of both sides )
x =
=
= 5
