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...