zero pressure angle

minimum pressure angle

maximum pressure angle

there is no such direction

Buttress threads

Square threads

Knuckle threads

V-threads

Acme

Square

Buttress

All of the above

50 degree

40 degree

60 degree

55 degree

to reduce hysteresis effect

to give linear relation between applied strains and resistance change

to increase sensitivity

to reduce or eliminate the effect of variation in ambient temperature