 Hello friends, let's discuss the following question. It says, find the surface area of a sphere of diameter 14 centimeter 21 centimeter and 3.5 meter. Let us first know the formula for surface area of sphere. It is equal to 4 pi r square, where r is the radius of the sphere. Value of pi is 22 upon 7. So this knowledge will work as key idea for the question. Let us now move on to the solution and let us discuss the first part. The diameter given to us is 14 centimeter and we know that the diameter is twice of the radius or we can say that radius is half of the diameter. So radius is 14 upon 2 centimeter that is 7 centimeter. Now surface area of sphere is 4 pi r square and the unit of diameter is given to be centimeter. So the unit of surface area will be centimeter square. Let us now substitute the values of pi and r in the formula. So we have 4 into 22 upon 7 into 7 square that is 4 into 22 upon 7 into 7 into 7 and multiplying 22 with 4 and 7 gives us area, surface area as 616 centimeter square. Let us now discuss the second part. The diameter of the sphere given to us is 21 centimeter. So the radius half of the diameter, so it is 21 upon 2 centimeter that is 10.5 centimeter. Now the surface area of sphere is 4 pi r square centimeter square. So substitute the values of pi and r that is 4 into 22 upon 7 into 10.5 into 10.5 centimeter square and simplifying this we get the area as 1386 centimeter square. Let us now discuss the third part the diameter of the sphere given to us as 3.5 meter. So the radius is half of the diameter that is 3.5 upon 2 meter dividing 3.5 by 2 gives us 1.75 meter. So the radius is 1.75 meter. Now the surface area of sphere is 4 pi r square pi is 22 upon 7 r is 1.75 meter. Now since the unit of diameter is in meters so the unit of surface area will be meter square which is equal to 269.5 upon 7 meter square which is again equal to 38.5 meter square. So the surface area of the sphere having diameter as 3.5 meter is 38.5 meter square. Hence answer to the first part of the question is 616 centimeter square and to the second part answer is 1386 centimeter square and to the third part answer is 38.5 meter square. So this completes the question. Bye for now. Take care. Have a good day.