H, I, O, and X have rotational symmetry.
E s i o
ALL letters have at least one line of rotational symmetry. However - if you mean reflective symmetry, the letters F, G, J, L, P, Q, R, S, & Z do not.
The letters H and Z have both line symmetry and rotational symmetry
H, I, N, S, X and Z. I make that 6, not 3! And O has 180 degree symmetry and more!
H, I, O, and X have rotational symmetry.
H i n o s x z
They are H, I, N, O, S, X and Z.
There are seven: B, H, I, O, S, X, Z
A B C D E H K M U V W X Y * * * * * What? Most of these letters do not have rotational symmetry and so cannot have rotational AND line symmetry. Or did the meaning of AND change last night? The only upper case letters with both are H, I, O, X
Eleven of them - AHIMOTUVWXY
The rotational symmetry of a plane object is the number of times it will look exactly like its original shape when you rotate it through 360 degrees in its plane. A whole alphabet has no rotational symmetry but some letters in an alphabet may have rotational symmetry. The number of symmetries depends on the alphabet, whether the letters are in upper or lower case as well as the font used.
Seven
There are 10 letters in the alphabet that achieve rotational symmetry when displayed in their capital form. These letters: A, H, I, M, O, U, V, W, X, and Y.
H, I, N, O, S, X, Z
letter o and x
A figure has rotational symmetry when it can rotate onto itself in less than a full rotation.