Determine the engineering strain $($e$),$ true strain reduction in cross section $($r$)$ for

each of the following cases:

a$)$ extension from L to $1\mathrm{.}1$h

b$)$ compression from h to $0\mathrm{.}9$h

c$)$ Extension from L to $2$L

d$)$ Compression from h to $2$

e$)$ Hypothetical case of reducing to zero thickness.