"ArcSegment" can't be drawn semi-circle correctly along the circle

* .NET Core Version: 3.1
* Windows version: Windows 10 Enterprise
* Does the bug reproduce also in WPF for .NET Framework 4.8?: Yes/No
* Is this bug related specifically to tooling in Visual Studio (e.g. XAML Designer, Code editing, etc...)? If yes, please file the issue via the instructions [here](https://docs.microsoft.com/visualstudio/ide/how-to-report-a-problem-with-visual-studio?view=vs-2019).
* Security issues and bugs should be reported privately, learn more via our [responsible disclosure guidelines](https://github.com/dotnet/wpf/blob/master/README.md#reporting-security-issues-and-security-bugs).

**Problem description:**
"ArcSegment" can't be drawn semi-circle correctly along the circle that was drawn by "Ellipse":
```csharp

```

**Actual behavior:**

**Expected behavior:**
"ArcSegment" can be drawn semi-circle correctly along the circle that was drawn by "Ellipse", Or how can I achieve that? Thanks.

**Minimal repro:**