You can put this solution on YOUR website! (1) cos(400)*sec(40) = cos(40)*(1/cos(40)) = cos(40)/cos(40) = 1
(2) sin(-180/12)*csc(25*180/12) = -sin(15)*(1/sin(15) = -1
(3) sin(-20)/cos(20) + tan(20) = -sin(20)/cos(20) + tan(20) = -tan(20) +
tan(20) = 0
In the tan function of (3), I assume you meant 20, not 200.