A quarter circle shape can be created easily in keynote.
How to create a quarter circle shape
Select Shape and Circle in the toolbar.
A circle is created.
To improve the visibility, select 「No Fill」 and 「Line」 in Fill tab.
Right click the circle and select 「Make Editable」.
The vertexes becomes editable.
Click the lower left vertex, and delete by pressing the delete key.
The shape changes.
Double click the upper left vertex and the lower right vertex.
The shape becomes a half circle.
Click the midpoint between the upper left vertex and the lower right vertex.
The midpoint is created.
Click the midpoint between the upper left vertex and the upper right vertex.
The midpoint is created.
Click and delete the lower right vertex.
The shape changes.
Double click the lower vertex and the right vertex.
The shape becomes a quarter circle.
Press the escape key.
Editing is ended.
A quarter circle is completed.
The way to save to My Shapes
It is convenient to save the quarter circle to My Shapes.
Right click the the quarter circle, and select 「Save to My Shapes」.
Enter the name, and press the enter key.
The quarter circle is ready to use.