In the adjoining figure, show that +++++=360°
Proof
In triangle BDF,
++ = 180°[Sum of angles of triangle] _______________ (i)
In triangle BDF,
++ = 180°[Sum of angles of triangle] _______________ (ii)
From equation (i) and (ii),
(++) + (++) = (180°+180°)
⇒ +++ ++ = 360°Proved.