A:π12
B:π4
C:π6
D:π3
②y=tan(x+ π4 )的一个对称中心是( π4 ,0);
③若α,β是第一象限角,且α<β,则tanα<tanβ,
④cos1<sin1<tan1.
其中所有正确命题的序号是____.
I didn't know what to do, but then an idea suddenly ____ me.