Question

Transform
arctan x + arctan y = pi/4 into algebraic expression

A) x+xy-y = 1
B) x-xy-y = 1
C) x+xy+y = 1
D) x-xy+y = 1

Plsss help

Answer 1

using the sum of tangents formula,

tan(arctan x + arctan y)
=

tan(arctanx)+tan(arctany)
----------------------------- = tan(pi/4)
1 - tan(arctanx)-tan(arctany)

(x+y)/(1-xy) = 1
x+y = 1-xy
x+xy+y = 1