I covered this previously.
Sin(theta)=sin(theta+360) in degrees
Sin(-theta)=sin(Theta) in degrees
sin(-20)=-sin(20) =-sin(20+360)=-sin(380)
then...
Tan(-theta)=-tan(theta).
Your refusal to post some sort of a meaningful name in the name box is not helping you get meaningful assistance.
Pre Calculus
why is sin(-20)/cos 380
equal to tan (-200)
1 answer