Gokyo Shumyo, Section 1, Problem 80 / Solution

Continuation  

threatens to capture three to make an eye. If White resists, makes miai of a and b.

Variation at 7  

"Watch your step" : Black needs to pay attention to the timing. Squeezing without cutting first won't work.

Failure at 1  

Starting at the other vital point of the L-group does not take advantage of the weakness in White's position.

threatens to capture only two stones, not enough to make an eye, so White can take time to defend at .