www.reference.com/article/area-semicircle-ac74ac6fb847ce40

To find the area of a semicircle, use the formula 1/2(pi x r^2). You need the value of "r," or radius of the circle, and pi.

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The area of a semicircle is (?*R*R)/2. This means the radius of the semicircle is squared, multiplied by the constant pi, then divided by 2.

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To calculate the area of a rectangle, multiply the length of the rectangle by its width. You need to know the length and width of the rectangle. A ruler, a pen, a paper and a divider are helpful in completing this task.

www.reference.com/article/determine-circumference-semicircle-e44c79f6976ca3d2

The perimeter of a semicircle is 1/2 of the circumference of the corresponding complete circle plus the diameter of the circle. The distance around the outside of a semicircle is generally called its perimeter.

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A rectangle is a four-sided plane figure, or any quadrilateral, with four right angles. Opposite sides of a rectangle are parallel and equal in length.

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The area of a rectangle is calculated from its width and height. Since a square is also a rectangle, the area of such polygons is also determined using the formula "area = width x height."

www.reference.com/article/can-rectangle-square-4d7642f7d2b34d2f

It is possible for a square to be a rectangle, but it is impossible for a rectangle to be a square. In order to be a square, the shape must contain four straight sides with 90-degree angles that are all the same length.