What is the value of {sin (90 – x) cos [π – (x – y)]} + {cos (90 – x) sin [π – (y – x)]}?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. (–cos y)
{sin (90 – x) cos [π – (x – y)]} + {cos (90 – x) sin [π– (y – x)]}
⇒ – cos x . cos (x – y) – sin x . sin (x – y)
⇒ – cos (x – x + y)
⇒ – cos y