What's the difference between 4sin40 and tan40? Please write down the detailed process In the middle is the minus sign

What's the difference between 4sin40 and tan40? Please write down the detailed process In the middle is the minus sign

4sin40-tan40=(4sin40cos40-sin40)/cos40=(2sin80-sin40)/cos40=(2cos10-sin40)/cos40=[2cos10-sin(30+10)]/cos40=[2cos10-1/2*cos10-√3/2*sin10]/cos40=(3/2*cos10-√3/2*sin10)/cos40=√3*(√3/2*cos10-1/2*sin10...