Update 求平方根.md

Author: CompetitiveLin

Dichotomy/求平方根.md

@@ -31,3 +31,28 @@ public class SquareRoot {
 
 ```
 
+
+
+Go 语言：
+
+```go
+package main
+
+import "fmt"
+
+func main() {
+	num := 8
+	target, left, right := float64(num), float64(0), float64(num)
+	for right-left > 1e-7 {
+		mid := (left + right) / 2
+		if mid*mid > target {
+			right = mid
+		} else {
+			left = mid
+		}
+	}
+	fmt.Println(left)
+	fmt.Println(right)
+}
+```
+