This week in Math, I learned how to calculate the surface area of a sphere. All you have to do is insert the measurements into this formula: 4πr^2 and you will find your answer. In this formula, you will need either the radius or the diameter which you can then turn to radius.
The radius is the distance between the centre of the circle to the outer edge and is represented by “r” in the diagram above. If you are given the diameter, represented by “d” above, all you need to do is divide that number by 2 and take that number.
Let’s say for example that the radius(r) of the circle above was 2. All you would need to do is plug that number into the formula(4πr^2) to figure out your answer like this on your calculator:
SA = 4πr^2 = 4·π·2^2 ≈ 50.26548
This can be used when measuring out wrapping paper for a spherical gift. If you plan to give someone a ball this Christmas, you can use this formula to calculate the surface area of that ball so you don’t waste any wrapping paper.