According to vsepr theory the molecular geometry for ch3+ is

The molecular geometry for  is trigonal planar.

Explanation

Formula used for calculating molecular weight:

where,

V = number of valence electrons present in central atom  = 4

N = number of monovalent atoms bonded to central atom = 3

C = charge of cation  = +1

A = charge of anion  = 0

Now we have to determine the hybridization of the  molecules.

Bond pair electrons = 3

Lone pair electrons = 0

The number of electrons are 6 that means the hybridization will be and the electronic geometry of the molecule will be trigonal planar.

As there are no lone pair of electrons,  the molecular geometry also will be trigonal planar.