0 votes 0 votes Let $S$ be the set of all $3 \times3$ matrices $A$ with integer entries such that the product $AA^{t}$ is the identity matrix. Here $A^{t}$ denotes the transpose of $A$. Then $\left | S \right |$ = $12$ $24$ $48$ $60$ TIFR tifrmaths2016 + – soujanyareddy13 asked Aug 30, 2020 • edited Oct 1, 2020 by soujanyareddy13 soujanyareddy13 196 views answer comment Share Follow See 1 comment See all 1 1 comment reply Shiva Sagar Rao commented Apr 30, 2021 reply Follow Share https://math.stackexchange.com/questions/1661038/how-to-count-the-number-of-integer-matrices-with-inverse-equal-to-transpose https://math.stackexchange.com/questions/2038752/how-many-3-times-3-integer-matrices-are-orthogonal 0 votes 0 votes Please log in or register to add a comment.