Math  /  Geometry

Question```latex \text{Find the perimeter of a composite shape that includes a semicircle with a diameter of } 7 \text{ ft.} ```

Studdy Solution

STEP 1

What is this asking? We need to find the total length around a shape that's like a half-circle! Watch out! Don't forget that perimeter includes *both* the curved part *and* the straight part of the semicircle.

STEP 2

1. Calculate the circumference of the full circle.
2. Calculate the circumference of the semicircle.
3. Calculate the total perimeter.

STEP 3

Alright, let's **start** by finding the circumference of the *whole* circle, even though we only have half of one.
The formula for the circumference of a circle is C=2πr C = 2 \cdot \pi \cdot r , where C C is the circumference and r r is the radius.

STEP 4

We're given the **diameter**, which is 7 7 feet.
The radius is *half* the diameter, so r=72=3.5 r = \frac{7}{2} = 3.5 feet.

STEP 5

Now we can **plug** our radius into the circumference formula: C=2π3.5 C = 2 \cdot \pi \cdot 3.5 .

STEP 6

Let's **calculate** that! C=2π3.5=7π C = 2 \cdot \pi \cdot 3.5 = 7\pi feet.
So, the circumference of the *full* circle is 7π 7\pi feet.

STEP 7

Since we're dealing with a *semi*circle, we need *half* the circumference of the full circle.

STEP 8

Let's **divide** the full circumference by 2 2 : 7π2 \frac{7\pi}{2} feet.
This is the length of the curved part of our semicircle.

STEP 9

Remember, the perimeter is the total distance around the shape.
We've got the curved part, which is 7π2 \frac{7\pi}{2} feet, but we also have the straight edge, which is the **diameter** of the semicircle!

STEP 10

We know the diameter is 7 7 feet.
So, to get the **total perimeter**, we **add** the curved part and the diameter: 7π2+7 \frac{7\pi}{2} + 7 feet.

STEP 11

The perimeter of the composite shape is 7π2+7 \frac{7\pi}{2} + 7 feet.

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