Question

usl 1/2 cool down
name: ______
period: ______
find the area of each figure below. be sure to use correct units and round to the nearest tenth if necessary.
1)
(image of a circle with radius 5 cm)
2)
(image of a rectangle with length 10 cm and width 7.1 cm)
3)
(image of a triangle with base 8 in and height 4.7 in)
4)
(image of a right triangle with legs 12 in and unknown, hypotenuse 13 in)

Explanation:

1) Area of the Circle

Step1: Recall the formula for the area of a circle.

The formula for the area of a circle is \( A = \pi r^2 \), where \( r \) is the radius. Here, \( r = 5 \, \text{cm} \).

Step2: Substitute the radius into the formula.

\( A = \pi (5)^2 = 25\pi \approx 25 \times 3.1416 \approx 78.5 \, \text{cm}^2 \)

2) Area of the Rectangle

Step1: Recall the formula for the area of a rectangle.

The formula for the area of a rectangle is \( A = \text{length} \times \text{width} \). Here, length \( = 10 \, \text{cm} \) and width \( = 7.1 \, \text{cm} \).

Step2: Multiply the length and width.

\( A = 10 \times 7.1 = 71.0 \, \text{cm}^2 \)

3) Area of the Triangle

Step1: Recall the formula for the area of a triangle.

The formula for the area of a triangle is \( A = \frac{1}{2} \times \text{base} \times \text{height} \). Here, base \( = 8 \, \text{in} \) and height \( = 4.7 \, \text{in} \).

Step2: Substitute the base and height into the formula.

\( A = \frac{1}{2} \times 8 \times 4.7 = 4 \times 4.7 = 18.8 \, \text{in}^2 \)

4) Area of the Right Triangle

Answer:

s:

1. \( \boldsymbol{78.5 \, \text{cm}^2} \)
2. \( \boldsymbol{71.0 \, \text{cm}^2} \)
3. \( \boldsymbol{18.8 \, \text{in}^2} \)
4. \( \boldsymbol{30.0 \, \text{in}^2} \)