If the projection of the vector on the sum of the two vectors and is 1, then is equal to ____.
Answer: 5
Solution
The sum of the two vectors is
and with ,
The projection of on is , so , which already forces . Squaring,
giving , so . This satisfies , and then with . Hence .
and with ,
The projection of on is , so , which already forces . Squaring,
giving , so . This satisfies , and then with . Hence .
JEE Main · 2021 · 26 Aug 2021 · Shift 2 · Integer answer