A ladder 8m long rests against a house. If the house is 6m high and the bottom of the ladder is 2m from the house, how much of the ladder extends beyond the roof?

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is