diff --git a/js/index.js b/js/index.js
index 3be1f60..7276f6a 100644
--- a/js/index.js
+++ b/js/index.js
@@ -1,10 +1,8 @@
 "use strict";
-function sum(...nums) {
-    let total = 0;
-    for (let num of nums) {
-        total += num;
-    }
-    console.log(`合計は${total}です`);
+function getTriArea(base, height) {
+    let area = 0;
+    area = base * height / 2;
+    return area;
 }
-sum(1, 2, 3, 4);
-sum(5, 10);
+let menseki = getTriArea(4, 3);
+console.log(`面積は${menseki}です`);
diff --git a/src/index.ts b/src/index.ts
index 65c7890..244719f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,9 +1,8 @@
-function sum(...nums:number[]):void{
-    let total =0;
-    for(let num of nums){
-        total +=num;
-    }
-    console.log(`合計は${total}です`);
+function getTriArea(base:number,height:number)
+:number{
+    let area:number=0;
+    area=base*height/2;
+    return area;
 }
-sum(1,2,3,4);
-sum(5,10);
\ No newline at end of file
+let menseki=getTriArea(4,3);
+console.log(`面積は${menseki}です`);
\ No newline at end of file