I have two problems
1) Express cot 138° 15' 10'' as the same function of a positive acute angle and then find its value.
2) Using exact values find the numerical value of tan 225°+tan(-45°)
tan(-45°) is in 4th quadrant?
Use the identity tan(180°+x)=tan x for accute x.
Thus,
tan 225°=tan(180°+45°)=tan 45°=1.
For the second tangent, tan(-45°), use the identity,
tan(-x)=-tan x.
Thus, tan(-45°)=-tan(45°)=-1.
Thus,
1+(-1)=0.
Yes, just add 360° once and you get,tan(-45°) is in 4th quadrant?
360°-45°=315°
Which is an angle in the 4th quadrant because,
270°<x<360°