Question

[Lê Thành Trung]

The area of a rectangle ABCD is 56cm2. Given a random point E inside of ABCD.Find the total area of triangles AED and BEC.

Answer 1

[Hoàng Ngọc Bảo Khuê]

In rectangle ABCD, AC = BD, HI = AB

We have: S"AED" + S"BEC"

= AC x HE : 2 + BD x EI : 2

AC = BD so  AC x HE : 2 + AC x EI : 2

= AC x (HE + EI) : 2

= AC x HI : 2

= AC x AB : 2

Area of this rectangle is 56cm2, or AC x AB, so:

= 56 cm2 : 2

= 28 cm2

Result: 28 cm2