What is Geometric isomerism and Why 2-Methyl But-2-ene does not show this type of isomerism?

Geometrical isomerism:

• A chemical compound having the same molecular formula as another but a different geometric configuration, as when atoms or groups of atoms are attached in different spatial arrangements on either side of a bond or a ring. This type of isomerism is shown by unsaturated open chain hydrocarbon of closed chain hydrocarbon. The difference in the orientation of bond about c= c in space creates isomers which is known as geometrical isomerism.
• Geometrical isomerism is generally found with compounds having coordination numbers 4 and 6.

2-Methyl-2-butene doesnot show geometrical isomerism because Cis/Trans Isomerism occurs when there are two different groups on each side of the C=C bond. While in this compound, methyl group is present on both double bonded carbon as it is shown by given structure:

So in this if we rotate along with C=C, then two different orientation will not be formed in this compound, so it does not show geomatrical isomerism.