The structure of I3+ is bent or V-shaped and the hybridization is sp3
The formula for determining the hybridization is
1/2{No:of valence electron in central atom+ Monovalent atom attached to central metal atom+anionic charge-cationic charge}
Applying 1/2[7+2-1+0] = 4 = sp3
The central atom has 6 electrons because of the one +ve charge
lone pair will be upside thus makes a bent shape