수잔인가요 VS 수잔이에요

Please Why we use “수잔인가요” ?? why this “인가요” to mean “이에요”

“인가요” is mean of conformation in question sentence. and " 이에요" is definite meaning. for example,

A: what should i call you?

B :Susan

as you can see the sentence in above, “이에요” is not exist expression in English.

“이에요” is used when you have to polite answer as a meaning of end of word.
“인가요” is also used when you say politely in question.