Question

A cone has a diameter of 7 cm and a slant height of 15.5 cm. What is the surface area of the cone?

Apply this formula: SA = πr2 + πrl

1. Find the radius of the measure: r =
d
2
=
7
2
= 3.5 cm

2. Substitute measures into the formula: SA = π(3.52) + π(3.5)(15.5)

3. Simplify the power and multiply: SA = 12.25π + 54.25π

4. Add to simplify: SA =
π cm2

Answer 1

Answer:66.5 cm2

Explanation:

Answer 2

Total surface area of the cone = 208.81 sq cm

Explanation:

Diameter of the cone (d) = 7 cm

Slant height (L) = 15.5 cm

1) The radius of the cone= Half of the diameter

= 7/2 cm = 3.5 cm

⇒ r = 3.5 cm

Now, Total surface area of the cone =
`\pi r^(2)  + \pi rl`

taking π = 3.14

We get
`\pi r^(2)   = 3.14 * 3.5 * 3.5 = 38.465 cm^(2)`

and πrl = 3.14 x 3.5 + 15.5 = 170.345

So, Total surface area of the cone = 38.465 + 170.345 = 208.81 sq cm