Complex Numbers And Quadratic Equations question 303
Question: $ \cos (x+iy) $ is equal to [RPET 2001]
Options:
A) $ \sin x\cosh y+i\cos x\sinh y $
B) $ \cos x\cosh y+i\sin x\sinh y $
C) $ \cos x\cosh y-i\sin x\sinh y $
D) None of these
Show Answer
Answer:
Correct Answer: C
Solution:
It is obvious.