diff --git a/25 2.py b/25 2.py
new file mode 100644
index 0000000..191f9d5
--- /dev/null
+++ b/25 2.py	
@@ -0,0 +1,11 @@
+A = [3, 4]
+B = [1, 2]
+
+A_plus_B = [A[0] + B[0], A[1] + B[1]]
+print("A + B =", A_plus_B)
+
+two_A = [2 * A[0], 2 * A[1]]
+print("2 × A =", two_A)
+
+norm_A = (A[0]**2 + A[1]**2)**0.5
+print("A的模 =", norm_A)
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diff --git a/25 3.py b/25 3.py
new file mode 100644
index 0000000..5b3692f
--- /dev/null
+++ b/25 3.py	
@@ -0,0 +1,21 @@
+import math
+
+A = [1, 2, 3]
+B = [4, 5, 6]
+
+dot_product = A[0]*B[0] + A[1]*B[1] + A[2]*B[2]
+print("A·B =", dot_product)
+
+norm_A = math.sqrt(A[0]**2 + A[1]**2 + A[2]**2)
+norm_B = math.sqrt(B[0]**2 + B[1]**2 + B[2]**2)
+cos_sim = dot_product / (norm_A * norm_B)
+print("余弦相似度 =", cos_sim)
+
+A2 = [1, 0]
+B2 = [0, 1]
+dot_product2 = A2[0]*B2[0] + A2[1]*B2[1]
+norm_A2 = math.sqrt(A2[0]**2 + A2[1]**2)
+norm_B2 = math.sqrt(B2[0]**2 + B2[1]**2)
+cos_sim2 = dot_product2 / (norm_A2 * norm_B2)
+print("A=[1,0]与B=[0,1]的余弦相似度 =", cos_sim2)
+print("原因：两个向量正交（垂直），方向完全不同，点积为0，所以余弦相似度为0")
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diff --git a/2509165025.py b/2509165025.py
new file mode 100644
index 0000000..863b2a0
--- /dev/null
+++ b/2509165025.py
@@ -0,0 +1,7 @@
+s = "Hello"
+print("Hello 每个字符的ASCII码：")
+for char in s:
+    print(f"{char}: {ord(char)}")
+
+print("\n验证65对应的字符：")
+print(f"chr(65) = {chr(65)}")
\ No newline at end of file