Remember to add you units to the final answer. Is your sphere's surface area 314 inches big, or 314 miles big? The units need to be written as "units2," because this denotes area, otherwise known as "square units"
The full answer to the sphere in the pictures is: Surface Area = 314 units2.
The units you use are always the same ones used to measure the radius. If the radius is in meters, the answer will be in meters.
Advanced Tip: We square the units because area measures how many flat squares we could fit on the surface of the sphere. Say we measure the practice problem in inches. This means on a sphere where r=5, we could fit 314 squares on the surface of the sphere if the sides of every square are 1 inch long.
Understand surface area. The surface area of a sphere is the area covering the outside of the sphere -- think of it as the rubber covering a kickball or the surface of the earth. Because it is curved, it is much harder to measure the surface area of a sphere than a box, so we need an equation to determine the area.
Rotating a circle around it's axis (the center point) will produce a sphere. Think of spinning a coin on the table and how it appears to form a sphere. While it won't be explained here, this is where our equation comes from.
Advanced Tip: Spheres have a smaller surface area per volume than any other shape -- that means it can hold more things in a smaller area than any other shape.
-For today, concluded that find the absolute value of each integer. Then subtract the lesser absolute value from the greater. The sum has the sign of the integer with the greater absolute value.