Positive SSL
1 有一雙線螺紋,螺距為2mm,節圓直徑為20mm,導程角為θ,則tanθ=
A 5/π
B 4/π
C 1/5π
D 1/10π
tanθ=`L/(πD)` =`(2P)/(πD)` = `(2*2)/(π*20)` = `1/(5π)`