Another way to do a 90 degree counterclockwise rotation is to use this rule: (x, y) to (-y, x).
So, you would take each coordinates of the figure and apply this rule.
For example, let's use (5, 7).
The rule is to take the x coordinate and put it on the other side of y, and y becomes negative.
(-7, 5) , and for that point you would plot in the new location in order to perform a 90 degree counter clockwise rotation.