A rectangle with sides of 3 and 4 cm was cut into 2 triangles. The cut lines are 5 cm long.

A rectangle with sides of 3 and 4 cm was cut into 2 triangles. The cut lines are 5 cm long. Of these, they formed a triangle with a perimeter of 16 cm. What is its area?

When dividing any closed geometric flat figure (in this case it is a rectangle), the sum of the areas of the resulting parts is equal to the area of the original figure. That is, no matter how you cut the rectangle, and no matter how you connect its parts, the area of all its parts will be equal to the area of the rectangle itself. Find the area:

S = a * b = 3 * 4 = 12 (cm2).

Answer: the area is 12 cm2.