Question

find the area of each. use your calculators value of π. round your answer to the nearest tenth.
7)
a) 265.9 in² b) 254.5 in² c) 63.6 in² d) 307.9 in²
8)
a) 18.8 yd² b) 128.7 yd² c) 141 yd² d) 113.1 yd²
name each figure.
9)
a) cone b) square pyramid c) rectangular pyramid d) hexagonal pyramid
10)
a) square prism b) hexagonal pyramid c) pentagonal pyramid d) triangular pyramid
11)
a) trapezoidal prism b) triangular prism c) cone d) cylinder
12)
a) pentagonal pyramid b) triangular prism c) triangular pyramid d) square prism

Explanation:

Step1: Recall area formula for circle

The area formula of a circle is $A = \pi r^{2}$, where $r$ is the radius.

Step2: Solve for problem 7

For problem 7, if the radius $r = 9$ in, then $A=\pi\times9^{2}=\pi\times81\approx 3.14\times81 = 254.34\approx254.5$ in².

Step3: Solve for problem 8

For problem 8, if the diameter $d = 12$ yd, then the radius $r=\frac{d}{2}=6$ yd. So $A=\pi\times6^{2}=\pi\times 36\approx3.14\times36 = 113.04\approx113.1$ yd².

Step4: Identify 3 - D shapes

For problem 9, the base is a rectangle and it has triangular faces meeting at a vertex, so it is a rectangular pyramid.
For problem 10, the base is a triangle and it has triangular faces meeting at a vertex, so it is a triangular pyramid.
For problem 11, the shape has two circular bases and a curved surface, so it is a cylinder.
For problem 12, the shape has two triangular bases and three rectangular lateral - faces, so it is a triangular prism.

Answer:

1. B. 254.5 in²
2. D. 113.1 yd²
3. C. rectangular pyramid
4. D. triangular pyramid
5. D. cylinder
6. B. triangular prism