3, ' ' 3 9 9 9 3IN BN IB BN AB AC BN = AB = MM =CM = ⇒ = ⇔= − = − NN IM' 3 8 2 1 1 1

3, ' ' 3 9 9 9 3IN BN IB BN AB AC

BN = AB = MM =CM = ⇒ = ⇔= − = − NN IM' 3 8 2 1 1 1