Find the area of a figure obtained by cutting off from a square with side R of two right-angled triangles with a leg L

Find the area of a figure obtained by cutting off from a square with side R of two right-angled triangles with a leg L, whose vertices at right angles coincide with opposite vertices of the square.

Square area: R ^ 2.

The area of one triangle is equal to half of the product of leg L and leg L:

St = (L * L) / 2 = L ^ 2/2.

Area of two cut triangles:

2St = 2L ^ 2/2 = L ^ 2 (the result suggests that a square with side L can be added from two such triangles).

We obtain the area of figure S if we subtract the area of two triangles with legs L from the area of a square with side R:

Answer: S = R ^ 2 – L ^ 2.