RelativeLayout: Problème placement circulaire

Bonjour à tous,

je cherche à placer 9 images équidistantes en forme de cercle grâce à un relativelayout comparé à un centre.

J'ai presque réussi mais les 2 dernières images ne peuvent pas être placée correctement (cf. image avec l'avant dernière)

Ci-dessous, le code xml:

Code:

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<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_gravity="center"
    android:orientation="vertical" >
 
    <ImageView
        android:id="@+id/center"
        android:layout_width="0dp" 
        android:layout_height="0dp"
        android:layout_centerInParent="true"
        android:background="#FFFF0000"
    />
 
    <ImageView
        android:id="@+id/center_top_a_1"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_above="@id/center"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="50dp"
        android:background="#FF00FF00" />
 
    <ImageView 
        android:id="@+id/bottom_left_a_1"
        android:layout_width="40dp" 
        android:layout_height="40dp"
        android:background="#FF00FF00"
        android:layout_below="@id/center"
        android:layout_toLeftOf="@id/center"
        android:layout_marginRight="40dp"
        android:layout_marginTop="50dp"
    />
 
    <ImageView 
        android:id="@+id/bottom_right_a_1"
        android:layout_width="40dp" 
        android:layout_height="40dp"
        android:background="#FF00FF00"
        android:layout_below="@id/center"
        android:layout_toRightOf="@id/center"
        android:layout_marginLeft="60dp"
        android:layout_marginTop="50dp"
    />
 
 <ImageView
        android:id="@+id/center_top_b_1"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_toLeftOf="@id/center"
        android:layout_above="@id/center"
        android:layout_marginBottom="20dp"
        android:layout_marginRight="40dp"
        android:background="#FF00FF00" />
 
 <ImageView
        android:id="@+id/center_top_c_1"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_above="@id/center"
        android:layout_toRightOf="@id/center"
        android:layout_marginBottom="20dp"
        android:layout_marginLeft="40dp"
        android:background="#FF00FF00" />
 
 <ImageView
        android:id="@+id/center_left_b_1"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_toLeftOf="@id/center"
        android:layout_below="@id/center"
        android:layout_marginBottom="1dp"
        android:layout_marginRight="50dp"
        android:background="#FF00FF00" />
 <ImageView
        android:id="@+id/center_right_b_1"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_toRightOf="@id/center"
        android:layout_below="@id/center"
        android:layout_marginBottom="1dp"
        android:layout_marginLeft="50dp"
        android:background="#FF00FF00" />
 
      <ImageView
          android:id="@+id/center_right_c_1"
          android:layout_width="40dp"
          android:layout_height="40dp"
          android:layout_below="@+id/center"
          android:layout_marginBottom="60dp"
          android:layout_marginLeft="2dp"
          android:layout_toRightOf="@+id/center"
          android:background="#FF00FF00" />
 
</RelativeLayout>

Quelqu'un sait comment corriger ça?

Merci d'avance,

Nicolas