Video narration
How can the same square help you make one with twice its area? Start with a square sheet, each side s. Double every side, and the area becomes four times larger, not twice: both dimensions grow. Baudhayana's construction uses the diagonal-the line from one corner to the opposite. Draw it across the sheet. It divides the square into two equal right triangles. Now use that diagonal as the side of a new square. Call its length d. The diagonal squared equals the squares of the two sides meeting at a corner: d squared equals s squared plus s squared, or two s squared. So the new square's area is d squared, while the original sheet's area is s squared. The new one has exactly twice the area. Yes: your square's corner-to-corner diagonal becomes the new square's side, making its area twice the sheet's.