The point of intersection of the lines →r×→a=→b×→a and →r×→b=→a×→b is
→a
→b
(→a+→b)
(→a−→b)
→r×→a=→b×→a⇒(→r−→b)×→a=→0⇒→r−→b=t →aAlso →r×→b=→a×→b⇒(→b+t→a)×→b=→a×→b⇒→b×→b+t →a×→b=→a×→b⇒→0+t →a×→b=→a×→b⇒t →a×→b=→a×→b⇒t=1⇒→r=→a+→b