If the stress ratio is given by R, and the amplitude ratio is given by A, the ratio between the R and A is given as __________

If the stress ratio is given by R, and the amplitude ratio is given b

1.	If the stress ratio is given by R, and the amplitude ratio is given by A, the ratio between the R and A is given as __________
A.	A=R
B.	A=1/R
C.	A=(1-R)/(1+R)
D.	A=(1+R)/(1-R)
Answer» D. A=(1+R)/(1-R)