Two solid metal shafts, are connected by the gears shown. Given:

$a=40mm$

$b=190mm$

$c=20mm$

$d_1=70mm$

$d_2=160mm$

$G=170$GPa

a$)$ If the applied tourque on shaft $AB,T=190$ N$.$m$,$ then the tourque generated in shaft $EF=433\mathrm{.}2$ N$.$m $[$Absolute value$]$

One possible correct answer is: $434\mathrm{.}29$

b$)$ Discard your answer in Part $($a$)$ and considering $T_{EF}=490N.m$ and diameter $r_{EF}=55$ mm $,$ then the maximum shear stress in shaft $EF=$ MPa $[$Absolute value$]$

One possible correct answer is: $15$

c$)$ If the angle of twist of shaft $AB$ is not to be greater than $5\mathrm{.}5,$ and considering the applied torque on shaft $AB=190$ N$.$m$,$ then the minimum required shaft $AB$ diameter $=$ mm

$x$

One possible correct answer is: $12\mathrm{.}85$