The key here is to notice that the area of a circle is being defined as its height, the radius, times its “width”, half of a circumference.Īt this point, you may have noticed that I have been putting some terms in quotes, mainly the references to the “base” the reason for which is that it is made up of a group of arcs rather than a straight line. On the right sticky, the A in the upper formula has a rectangle by it, it contains length, and it contains height it refers to the area of a rectangle.On the right sticky, the A in the lower formula has a circle by it, it contains radius, and it contains half of a circumference it refers to the area of a circle.half the circumference is another dimension of the area formula of a rectangle (students may say length or width, base or height).the radius is one dimension of the area formula of a rectangle (students may say length or width, base or height).the radius is the r on the left, middle, and right stickies.half the circumference is found on the bottom portion of the circle on the left sticky, on the “base” of the middle sticky, and in the formula for the area of a circle on the right sticky.all three stickies have representations of the the area of a circle.Students may not come up with the last two bullets however, you can introduce them one at a time if you like on individual stickies.Ĭonnections between the left and middle stickies were discussed above additional connections could include : writing the formula for area of the circle or even one its halves.drawing the new figure more like a “rectangle” by cutting an end piece in half (bisecting the angle) and moving it.Students could create their own representations these might include: the arrow on the middle sticky seems to indicate moving part of the left side to the right side.the longer line is the “base” of the new figure.the longer line is one half of the circumference.the four open “slices” in the right sticky make up half of the new figure on the middle sticky.the four gray “slices” in the left sticky make up half of the new figure on the middle sticky.r, the radius of the circle, in the left sticky is the height of the new figure in the middle sticky.The curved line in the left sticky is equivalent to the longer straight line in the middle sticky The middle sticky has the area of circle organized so it is similar to a parallelogram, or a rectangle if you think of moving half of an eighth (1 sixteenth).
Shading is not representative of the entire area of the circle it represents half the area of the circle. Attention, the result is expressed in the same unit as the one you entered, but it is square.Both stickies represent the the area of a circle
You simply enter the length then the width to get the surface (also called area). To simplify the calculation, use our rectangle area calculator above. Take as an example a rectangle with a length of 20 cm and a width of 15 cm: To calculate the area of a rectangle (r), multiply the length (A) by the width (B).
Formula for the area of a Rectangle Calculator Especially when you want to repaint your walls or change your tile: Before buying the material, it is recommended to know the surface to be developed to save money. The calculation of a surface is regularly used to calculate an area to be covered. The sides of a rectangle are equal and parallel two by two. More about the rectangle: A rectangle is a quadrilateral (polygon with 4 sides) with 4 right angles. What is called an area or surface is the internal measure of a geometric form. Calculate the area of a rectangle! All you have to do is use our online calculator with the explanatory formula! Discover geometry differently with Calculator Market! What is the area of a Rectangle?