How is it possible? - Puzzle

I gave up on this one - any ideas anyone

Yes Polly, but I had to look it up:

Spoiler:

The bigger shape is not a true triangle. If you hold a straight edge against the sloping line you will see that the upper shape bulges very slightly while the lower shape is very slightly hollow. The tiny difference in total area is enough to account for the missing square.

Yes Polly, but I had to look it up:

Spoiler:

The bigger shape is not a true triangle. If you hold a straight edge against the sloping line you will see that the upper shape bulges very slightly while the lower shape is very slightly hollow. The tiny difference in total area is enough to account for the missing square.

Quite right Dutchman.

You'd be surprised how many engineers are caught out with that one.

Cheater

Cheater

I only looked it up after I'd struggled with it for hours Polly. I already had a pretty good idea what the solution was before I looked it up and you'd be surprised how many totally incorrect solutions there are online!