Content

• Steps
• Tips
• Warnings

Finding the area of ​​a cone is quite simple. It all depends on what data you have. We will tell you what you need to know in order to find the area of ​​a cone.

Steps

1. 1 Find out the radius of the base of the cone. If you have a diameter, divide it by two to get the radius. If you have the length along the generatrix of the cone and the length of the perpendicular, use the Pythagorean theorem.
2. 2 Write down the radius somewhere on the side. You will need to do calculations.
3. 3 Find the area of ​​the base of the cone. To do this, you need to multiply the number Pi by the radius squared.
   • If it is written in the conditions of the problem that you do not need to find the exact numerical value, you do not have to multiply by the pi value, just write down the result along with pi. For example, if the radius is 3, then the base area is 9 pi.
   • Otherwise, use the numerical value Pi = 3.14, calculate the result of the multiplication on the calculator.
     • You can round pi to three decimal places.
4. 4 Write your answer on the side, mentioning that this is the base area.
5. 5 Find out the length along the generatrix of the cone. This is the height of the perpendicular connecting the top of the cone and its base (if the cone is straight, then the center of the base).
   • The radius, the height of the perpendicular and the height along the generatrix are related by the Pythagorean theorem.
6. 6 Multiply the generatrix height by the radius by Pi.
7. 7 We got the area of ​​the lateral surface of the cone. Write it down.
8. 8 Add to it the base area we found earlier.
9. 9 So we got the area of ​​the cone. Write down your answer.

Tips

• Usually numbers up to 20 are written with precision to two decimal places, numbers from 20 to 100 are written with precision to 1 decimal place, and numbers over a hundred are rounded to the nearest whole number.
• The Pythagorean theorem is applied to the radius, the height of the perpendicular and the height along the generatrix, which is the hypotenuse: (radius) + (height of the perpendicular) = (height along the generatrix)

Warnings

• If there is a square root in the numerical value of the radius or height along the generatrix, you will not be able to complete Step 8.