Update index.html

Typical age range

Author: Gmac4247

index.html

@@ -689,7 +689,7 @@ <h3 style="margin:7px">Volume of a Cube</h3>
 <meta itemprop="isFamilyFriendly" content="true">
 <meta itemprop="keywords" content="Core Geometric System, Exact Geometric Calculations, Analysis, Engineering Design Solutions, Computer Graphics Rendering, Algorithm Optimization, Navigation">
 <meta itemprop="operatingSystem" content="Web">
-<meta itemprop="typicalAgeRange" content="6-18">
+<meta itemprop="typicalAgeRange" content="12-18">
 <meta itemprop="url" content="https://basic-geometry.github.io">
 <h3 itemprop="name" style="margin:7px">Trigonometry</h3>
 <br>