Question

prove that tan(270-A)=cotA

Answer 1

tan(n.90±A ) = ±cotA if n is odd ,

tan(n.90±A ) = ±tanA if n is even .

tan(270-A ) = tan ( 3*90 -A)

270-A lies in 3rd Quadrant ,Tan(270-A) is positive

= +cotA

hope helped !