Since the line PM is ⟂ to the given line x+y=3 ∴‌‌
y1−3
x1−2
×(−1)=1 ⇒y1−3=x1−2 ⇒x1−y1+1=0 . . . (i) and also the points lies on the given line x1+y1−3=0 . . . (ii) On solving Eqs. (i) and (ii), we get ∴‌‌x1=1,y1=2 ∴ The co-ordinates of M are (1,2).