Question

four congruent isosceles right triangle are cut from the four corner of a square with side of 20 unit the length of one leg of the triangle is equal to 4 unit the area of the remaining octagon is​

Answer 1

The area of remaining octagon is 168 units.

Let the square be = A

Let the triangle be = B

Finding the area of  square A

Area of square = (side)²

A = 20 × 20

= 400 square units

Finding the area of small triangle = B

Area of Triangle = 1/2 × l × b

B = (1/2) × 4 × 4

= 8 square units

Area of the octagon = Area of triangles - Area of square  

= A - 4B

= 200 - 4 × 8

= 168 square units

Therefore, the area of remaining octagon is 168.