"whether" is correct and required. Without it the sentence wouldn't make sense.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
CliveConsider these examples.C
eg I am interested in knowing whether you like tea or you like coffee.
eg I am interested in knowing if you like tea or you like coffee (but you may like Coke or you may like Pepsi).