I just kept on staring at the triangles to figure out if one was larger than the other. Then scaled the monitor to find the measurement of each sides: it seemed equal.

But when I created the triangles in computer using 12"x12" boxes as grids, and overlapping first triagle boundary to the second one, the difference seemed apparent. See the picture; the dotted line on second triangle is the boundary of the first triangle. The second triangle is bigger in space than the first triangle.

It's a good one. Its a visual trick.