Q(zq) is the foot of perpendicular drawn from P(zp) to the line az¯+za¯+b=0, b∈R and 'a' is complex number, then:
zqa¯+az¯p−zpa¯+b=0
zqa¯+2az¯p−zpa¯+b=0
2zqa¯+az¯p−zpa¯+b=0
zqa¯+az¯p−2zpa¯+b=0
Since a is perpendicular vector to the line.
zq−zp=λa, λ∈R
a¯(zp+λa)+a(z¯p+λa¯)+b=0
⇒ az¯p+a¯zp+b+2λaa¯=0
Also 2a¯zq−2a¯zp=2λaa¯
∴ az¯p+a¯zp+b+2a¯zq−2a¯zp=0
⇒ 2a¯zq+az¯p−a¯zp+b=0