Question: The default icon for toggling a `mat-expansion-panel` is `>`. Setting `hideToggle` true just hides the toggle icon. Is there any way to change it? I found nothing in the official documentation. I want to use `+` or `-` icon if the state is closed or opened respectively.

Answer: 
Give the name to the mat-expansion-panel say panel in the example. Use expanded property of the mat-expansion-panel to show or hide the + or - icon.

```
 <mat-expansion-panel #panel  hideToggle>
        <mat-expansion-panel-header>
             <mat-panel-title>
                        Buttons
             </mat-panel-title>
             <mat-icon >{{panel.expanded? 'remove' : 'add'}}</mat-icon>

        </mat-expansion-panel-header>

  </mat-expansion-panel>

```
add **hideToggle** to mat-expansion-panel :

```
<mat-expansion-panel (opened)="panelOpenState = true"
                             (closed)="panelOpenState = false" hideToggle>

```

and add icon:

```
 <mat-expansion-panel-header>
            <mat-icon>add</mat-icon>

```