Why is the `C-O-H` bond angle in alcohols slightly less than the tetrahedral angle whereas the C-O-C bond angle in ether is slightly greater?

Explanation

The bond angle in `C-underset(..)overset(..)(O)-H` in alchols is slightly less than tetrahedral is slightly less than tetrahedral angle (`109^(@) 28')`. It is due to the repulsion between the unshared electron pairs of oxygen. In alcohols, two lone pair of electrons are present. Therefore, three is comparatively more repulsion and less and angle.
The `C-O-C` bond angle in their slightly greater than the tetrahderal angle due to the repulsive interaction between the two bulkyl (-R) groups.