Trapezoid US Trapezium UK Area ½ab h h vertical height. Area p x r 2 in terms of radius r. Area p4 x d 2 in terms of diameter d.
Multiply the radius by itself to square it.
Now find the area of the circle using the formula with radius as shown below. Area of a circle diameter. This variable is squared. The radius of the circle is the length of a straight line stretching from the center of the circle to the line of circumference.