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Yes, a rotation is an isometry.
Yes, translation is part of isometry.
A isometry is a transformation where distance (aka size) is preserved. In a dilation, the size is being altered, so no, it is not an isometry.
Yes. Being congruent is part of the definition of an isometry.
An isometry is a transformation in which the original figure and its image are congruent.
Shape remains constant as size increases.