When Peter does this, he is creating two sides of a right-angle triangle. The distance from his house to that point will be the hypotenuse of the triangle thus, to work out the length of the hypotenuse, we have to use Pythagoras Theorem! So:
a² + b² = c²
15² + 15² = c²
225 + 225 = c²
450 = c²
15√2 = c
21.21320344 = c
So, this rounded to the nearest tenth would be:
21.2 meters !
