Gokyo Shumyo, Section 1, Problem 96 / Solution

Failure  

Direct countermeasures against the cut fail. Black strikes at the 1-2 point. The enemy's key point is yours, so ...

Solution

Variation 1  

White lives by taking both 1-2 points. After , a and b are miai.

Variation 2  

If takes the second 1-2 point, White protects the cut.