If sin (A + B) = 1, where 0 < B < 45°, then what is cos (A – B) equal to?

If sin (A + B) = 1, where 0 < B < 45°, then what is cos (A – B) equ

1.	If sin (A + B) = 1, where 0 < B < 45°, then what is cos (A – B) equal to?
A.	sin 2B
B.	sin B
C.	cos 2B
D.	cos B
Answer» B. sin B