diff --git "a/LiiNi-coder/202602/07 BOJ \354\202\254\353\213\244\353\246\254.md" "b/LiiNi-coder/202602/07 BOJ \354\202\254\353\213\244\353\246\254.md"
new file mode 100644
index 00000000..8bd93932
--- /dev/null
+++ "b/LiiNi-coder/202602/07 BOJ \354\202\254\353\213\244\353\246\254.md"	
@@ -0,0 +1,37 @@
+```java
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+public class Main{
+	private static double X, Y, C;
+
+	public static void main(String[] args) throws IOException{
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		String[] t = br.readLine().split(" ");
+		X = Double.parseDouble(t[0]);
+		Y = Double.parseDouble(t[1]);
+		C = Double.parseDouble(t[2]);
+		double l = 0; // check(l) = true
+		double r = Math.min(X, Y); // check(r) = false
+		for(int i=0; i<100; i++){ //l, r 이 실수면 그냥 100번정도 하면 오차 내로 수렴하는 방식
+			double mid = (l + r) / 2.0;
+			if(check(mid)){
+				l = mid;
+			}else{
+				r = mid;
+			}
+		}
+
+		System.out.printf("%.3f\n", l);
+	}
+
+	private static boolean check(double w){
+		double h1 = Math.sqrt(X * X - w*w);
+		double h2 = Math.sqrt(Y * Y - w*w);
+		double cross = (h1 * h2) / (h1 + h2);
+		return cross >= C;
+	}
+}
+
+```