diff --git a/froglike6/README.md b/froglike6/README.md
index d979d30..09ec996 100644
--- a/froglike6/README.md
+++ b/froglike6/README.md
@@ -10,4 +10,5 @@
  | 6차시 | 2025.04.07 | 백트래킹| [N-Queen](https://www.acmicpc.net/problem/9663)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/24|
  | 7차시 | 2025.04.09 | 그래프 | [최소비용 구하기](https://www.acmicpc.net/problem/1916)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/27|
  | 8차시 | 2025.04.11 | 물리학 | [곰곰이와 시소](https://www.acmicpc.net/problem/26072)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/31|
+ | 9차시 | 2025.04.30 | 기하학 | [평행사변형](https://www.acmicpc.net/problem/1064)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/34|
  ---
diff --git a/froglike6/geometry/1064.py b/froglike6/geometry/1064.py
new file mode 100644
index 0000000..c539293
--- /dev/null
+++ b/froglike6/geometry/1064.py
@@ -0,0 +1,26 @@
+import math
+import sys
+input = sys.stdin.readline
+
+def main():
+    xA, yA, xB, yB, xC, yC = map(int, input().split())
+
+    cross = (xB - xA) * (yC - yA) - (yB - yA) * (xC - xA)
+    if cross == 0:
+        print(-1)
+        return
+
+    dAB = math.hypot(xA - xB, yA - yB)
+    dBC = math.hypot(xB - xC, yB - yC)
+    dCA = math.hypot(xC - xA, yC - yA)
+
+    s1 = dAB + dCA
+    s2 = dAB + dBC
+    s3 = dBC + dCA 
+
+    answer = 2 * (max(s1, s2, s3) - min(s1, s2, s3))
+
+    print(f"{answer:.15f}")
+
+if __name__=="__main__":
+    main()
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