A grid is 10 squares high and 10 squares wide. The distance between each grid square is 3 feet. The triangular viewing area of camera is shown. The right triangle has 2 sides with lengths of 5 grid squares. The area of the triangle is 112.5 feet squared. Alan wants to install security cameras in his store, which has dimensions of 30 feet by 30 feet. Each camera can view an area of approximately 112.5 ft2, with a viewing area shaped like a right triangle.

How many cameras will be necessary to cover the entire store?

.

If he places cameras only in the corners of the store, how much area is left uncovered?

ft2.