The math works out perfectly. This new 10.5” iPad would have the
exact same resolution as the 12.9” iPad Pro (2732 × 2048), but the
same pixel density of the iPad mini (326 ppi instead of 264 ppi).
Crunch the numbers, do a little Pythagorean Theorem, and you end
up with a screen 10.5” diagonal (10.47” to be precise, but none of
Apple’s stated screen sizes are exact). In terms of physcial
dimensions, the width of this 10.5” screen would be exactly the
same as the height of the iPad mini screen.