diff --git a/src/main/java/com/mathapp/problemGenerators/HighSchoolProblemGenerator.java b/src/main/java/com/mathapp/problemGenerators/HighSchoolProblemGenerator.java
index db8733d..cf6bdc1 100644
--- a/src/main/java/com/mathapp/problemGenerators/HighSchoolProblemGenerator.java
+++ b/src/main/java/com/mathapp/problemGenerators/HighSchoolProblemGenerator.java
@@ -42,7 +42,8 @@ public class HighSchoolProblemGenerator extends MiddleSchoolProblemGenerator {
 
       // 2c.【健壮性检查】检查这个新运算符是否会与三角函数的值构成除零错误
       boolean isTrigValueZero = (function.equals("sin") && angleInDegrees == 0) ||
-              (function.equals("tan") && angleInDegrees == 0);
+              (function.equals("tan") && angleInDegrees == 0)||
+              (function.equals("cos") && angleInDegrees == 90);
 
       // 如果新运算符是除法，且三角函数的值是0，则这是一个非法组合，必须重试
       if (connectingOperator == Operator.DIVIDE && isTrigValueZero) {