Please answer my grammatical question?

Question

(i have a book which i don't know how he got)

(this is the kind of question which we need to know how to solve)

are two sentences above correct?

because in grammar books, i have never seen that type of structure.

because the part of the sentence that follows interrogative word(how) is not the complete sentece, I thought the two sentences above are not correct.

Answer 1

The are correct, but very poorly written sentences. Regardless, they are not "technically" wrong, just ugly sentences.

PS: The last sentence is definitely wrong.

Answer 2

The are absolutely incorrect.  In sentence #1, the word "which" is being used in place of "but."  This is becoming a trend, and it's horrible.  It should read:  I have I book, but I don't know how he got it.  (Still a confusing sentence, but technically correct now.)

#2  This is the kind of question that we must solve.    OR   We need to know how to solve this question.

#3 Nobody understands why anybody would read this type of book.

   The problem with all the original sentences is the erroneous use of "which."  In addition, the writer failed to follow an important rule: keep it simple!  The original sentences are wordy and confusing.  They don't communicate the message and are grammatically stinted.