# Geometry

posted by .

The surface area of acone with height 15 cm is 500π square cm. Find the radius of the cone. Round your answer to two decimal places.

• Geometry -

The surface area

SA=Pi*r^2+Pi*r*s, s=sqrt(r^2+h^2)
500*Pi=Pi*r^2+Pi*r*sqrt(r^2+225)
500=r^2+r*sqrt(r^2+225)
500-r^2=r*sqrt(r^2+225)
(500-r^2)^2=(r*sqrt(r^2+225))^2
250000-1000r^2+r^4=r^2(r^2+225)
250000=1225r^2
r^2=250000/1225

## Similar Questions

1. ### geometry

A right cylinder has a radius of 3 and a height of 12. What is its surface area?
2. ### geometry/algebra

I asked this question yesterday, and I'm trying to understand it since I got the wrong answer - please explain: You need to make a soda can with a volume of 29 cubic inches. Find the surface area. calculate the following: a) How much …
3. ### geometry

Find the surface area of a cone with a slant height of 11 and a radius of 15. Use 3.14 for ð. Round your answer to the nearest tenth.
4. ### Help me with this math ms sue.

1. Find the lateral area of a cone with a radius of 7 ft. and a slant height of 13 ft. Use 3.14 for π and round to the nearest tenth. (1 point) 439.6 ft2 324.5 ft2 571.5 ft2 285.7 ft2 2. Find the surface area of a square pyramid …
5. ### MATH QUIZ PLS HELP!!!

1.Find the lateral area of a cone with a radius of 7 ft. and a slant height of 13 ft. Use 3.14 for ©£ and round to the nearest tenth. 439.6 ft^2 324.5 ft^2 571.5 ft^2 285.7 ft^2*** 2.Find the surface area of a square pyramid with …
6. ### Algebra 1--How Am I Supposed to Solve This?!

Suppose a cone and a cylinder have the same radius and that the slant height l of the cone is the same as the height h of the cylinder. Find the ratio of the cone's surface area to the cylinder's surface area. Area of cone: S = πrl …
7. ### math

Determine the surface area of a right circular cylinder shown below whose radius r is 7 feet and height h is 21 feet. Use π = 3.14. Round off your answer to two decimal places.
8. ### Math

What is the surface area and volume of a composite figure made up of a hemisphere and a cone in terms of pi?
9. ### MATHEMATICS

A SECTOR IS USED TO FORM ACONE IF THE RADIUS AND ANGLE OF THESECTOR IS 8CM AND 160 DEGREE RESPECTIVELY CALCULATE, THE RADIUS OF THE CONE ,VERTICAL HEIGHT, VERTICAL ANGLE, VOLUME AND TOTAL SURFACE AREA OF THE CONE
10. ### Calculus

A company needs to make a cylindrical can that can hold precisely 1.5 liters of liquid. If the entire can is to be made out of the same material, find the dimensions (radius and height) of the can that will minimize the cost. Round …

More Similar Questions