The right triangle formed is shown below
To find the slant height, x, we would apply the pythagorean theorem which is expressed as
hypotenuse^2 = one leg^2 + other leg^2
Looking at the triangle,
hypotenuse = x
one leg = 12
other leg = 7
By applying the pythagorean theorem,
x^2 = 12^2 + 7^2 = 144 + 49 = 193
x = square root of 193
x = 13.89
Rounding to the nearest whole number,
x = 14