New posts in Exceptional Isomorphisms

Extending the action $S_5$ on $2$-subsets of $\{1,\cdots,5\}$ to an action of $S_6$.

Group homomorphism from $SL_2 (\mathbb Z / 5 \mathbb Z)$ to $S_5$

Elementary isomorphism between $\operatorname{PSL}(2,5)$ and $A_5$

Isomorphism between $\mathfrak o(4,\mathbb R)$ and $\mathfrak o (3,\mathbb R) \oplus\mathfrak o (3,\mathbb R) $

Why is $SO(3)\times SO(3)$ isomorphic to $SO(4)$?