To find out how high up the building the ladder will reach, we can use the Pythagorean theorem which states that in a right-angled triangle, the square of the length of the hypotenuse (the ladder in this case) is equal to the sum of the squares of the other two sides.
Let x represent the height up the building that the ladder reaches. We can set up the equation as follows:
10^2 = 5^2 + x^2
100 = 25 + x^2
x^2 = 75
x = √75
x ≈ 8.66 m
Therefore, the ladder will reach approximately 8.66 meters up the building.