# Points in a square, surface

#### ghostfirefox

##### New member
Let E, F be such points inside the ABCD square that | ∢AEF | = | ∢EFC | = 90∘ and | AE | = 2, | CF | = 6 and | EF | = 6. Calculate the surface of ABCD.

#### skeeter

##### Well-known member
MHB Math Helper
$|AC| = 10$ ... see what you can do with that piece of information