I'll continue from

where the inv of tan:

sin,cos and tan are +ve at 1st quandrant(angle=@°),sin +ve at 2nd(angle=180°-@),tan+ve at 3rd(angle=180°+@°) and cos+ve at 4th(angle=360°-@°).

Invtan(-1/2)=26.6° and Intan(-3°)=71.6°

Therefore required angles are

(180°-26.6)°, (360-26.6)°,(180-71.6)°and(360-71.6)°

Sorry I don't haveagood programthat illustrate Maths symbols.