Math  /  Geometry

QuestionWhat is the surface area of this cone? Use π3.14\pi \approx 3.14 and round your answer to the nearest hundredth. \square square inches

Studdy Solution

STEP 1

What is this asking? We need to find the total surface area of a cone, meaning the area of the circular base and the curved surface. Watch out! Don't forget to include both parts of the cone's surface area: the circular base *and* the curved surface.
Also, don't mix up the slant height and the vertical height!

STEP 2

1. Area of the circular base
2. Area of the curved surface
3. Total surface area

STEP 3

The area of a circle is given by the formula A=πr2A = \pi \cdot r^2, where rr is the **radius**.
We're doing this because the base of the cone is a circle!

STEP 4

We are given that the **radius** is r=11r = 11 inches.
Let's plug that into our formula: A=π(11)2A = \pi \cdot (11)^2.

STEP 5

Calculating the **area** gives us A=π121A = \pi \cdot 121.
Remember, π\pi is approximately 3.143.14, so A3.14121A \approx 3.14 \cdot 121.

STEP 6

Multiplying gives us A379.94A \approx 379.94 **square inches**.
This is the **area of the circular base**.
Keep this number in mind, we'll need it later!

STEP 7

The **curved surface area** of a cone is given by the formula A=πrlA = \pi \cdot r \cdot l, where rr is the **radius** and ll is the **slant height**.

STEP 8

We know the **radius** is r=11r = 11 inches and the **slant height** is l=17l = 17 inches.
Plugging these values into the formula, we get A=π1117A = \pi \cdot 11 \cdot 17.

STEP 9

Using our approximation for π\pi, we have A3.141117A \approx 3.14 \cdot 11 \cdot 17.

STEP 10

Multiplying these numbers gives us A584.58A \approx 584.58 **square inches**.
This is the **area of the curved surface**.
Almost there!

STEP 11

To find the **total surface area**, we add the **area of the circular base** and the **area of the curved surface**.

STEP 12

From our previous calculations, the **area of the base** is approximately 379.94379.94 square inches, and the **area of the curved surface** is approximately 584.58584.58 square inches.

STEP 13

Adding these together, we get 379.94+584.58=964.52379.94 + 584.58 = 964.52 **square inches**.
This is our **total surface area**!

STEP 14

The surface area of the cone is approximately 964.52964.52 square inches.

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