Question

WILL MARK BRAINLIEST
A candle in the shape of a cone has a slant height of 20 cm and a diameter that measures 18 cm. What is the surface area of the candle? (Use 3.14 for pi and round to the nearest hundredth. Recall the formula SA=pi rl + pi r^2.)
536.94 cm^2
819.54 cm^2
1,821.20 cm^2
2,147.76 cm^2

Answer 1

Answer:

819.54 cm^2

Step-by-step explanation:

We are given

Slant height = l = 20cm

and

Diameter = d = 18 cm

We have to find radius first

r = d/2 = 18/2 = 9 cm

The formula for surface area is:

$SA = \pi rl+\pi r^2\\= (3.14 * 9 * 20) + (3.14 * (9)^2)\\=565.5+254.34\\=819.84\ cm^2$

As second option is nearest to calculated answer, it is the correct option ..

Answer 2

Answer: second option.

Step-by-step explanation:

We know that we can calculate the surface area of a cone with this formula:

$SA=\pi rl + \pi r^2$

Where "r" is the radius and "l" is the slant heigth.

We know that the radius is half the diameter, then the radius of this cone is:

$r=\frac{18cm}{2}\\\\r=9cm$

Since we know the radius and the slant height, we can substitute values into the formula, using 3.14 for π.

Therefore, we get:

 $SA=(3.14)(9cm)(20cm) + (3.14)(9cm)^2=819.54cm^2$