Answer:
=11.35 ft.
Step-by-step explanation:
The ladder, the flat surface the wall and the height up to the window form a trapezium.
The triangle that constitutes of the trapezium has the ladder as the hypotenuse, the distance between the two walls as base and the perpendicular distance from the base of the ladder to the window as height.
The height=20.35 ft-15 ft= 5.35 ft
Distance between the walls=10 ft
Hypotenuse²= base²+height²
H²=b²+h²
=10²+5.35²
=128.6225
H=√128.6225
=11.35 ft.
