How to check multiple checkboxes programmatically in a formGroup on reactive form?

I am using Angular2 RC 5, and trying to implement a reactive form (model driven)

I defined the checkboxes like so

usageRights : new FormGroup({
         all_usage   : new FormControl( '' ),
         digital     : new FormControl( '' ),
         outdoor     : new FormControl( '' ),
         print       : new FormControl( '' ),
         radio       : new FormControl( '' ),
         tv          : new FormControl( '' )
})

There is a button and when it is clicked, I like to check all the checkboxes in the group. My current implementation is using a function on click of the button but I cannot figure out how I can check these checkboxes in my ts file

My checkAll function

checkAll( control, e ) {
    e.preventDefault();
    console.log(control);
}

control is the formGroup(usageRights) that contains all the checkboxes, and it logs fine. I believe I can just use a variable in combination with [checked], then update the variable when clicked on the button but I feel like this is not the proper way of doing this.

Someone please tell me how this should be done. I am stuck.