Question

What is meant by odd or even multiple of pi/2 ?

Answer 1

odd multiple of pi/2 means
$((2 \times n) - 1) \times \pi \div 2$
where n=1,2,3........
even multiple of pi/2 means
$((2 \times n) + 1) \times \pi \div 2$
where n=0,1,2,3,4.........