wpf button storyboard trigger

Question

I am trying to make rectangle animation after clicking on a button.

xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions"

<Button Content="FirstButton" HorizontalAlignment="Left" Height="60" Margin="341,91,0,0" VerticalAlignment="Top" Width="91">
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="Click">
                 ??? <BeginStoryboard Storyboard="{StaticResource Storyboard1}"/>
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </Button>

What i need to write?

Answer 1

 <StackPanel>
    <Button Name="Button"/>
    <Rectangle>
        <Rectangle.Style>
            <Style TargetType="Rectangle">
                <Style.Triggers>
                    <DataTrigger Binding="{Binding ElementName=Button, Path=IsPressed}" Value="True">
                        <DataTrigger.EnterActions>
                            <BeginStoryboard>
                                <Storyboard>

                                </Storyboard>
                            </BeginStoryboard>
                        </DataTrigger.EnterActions>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </Rectangle.Style>
    </Rectangle>
</StackPanel>