Question

the stained - glass window shown is a half - circle. what is the perimeter of the window? use 3.14 for π. show your work. which of the following expressions can you use to find the circumference of a circle with radius 7 cm? select all the correct answers. a 2×7×π b 2×14×π c 7×π d 14×π e 49×π

Explanation:

Step1: Recall the formula for the circumference of a circle

The formula for the circumference of a circle is $C = 2\pi r$ or $C=\pi d$, where $r$ is the radius and $d$ is the diameter ($d = 2r$). Given $r = 7$ cm, then $d=14$ cm.

Step2: Analyze each option

• Option A: $2\times7\times\pi= 14\pi$ is correct as it is in the form of $2\pi r$ with $r = 7$.
• Option B: $2\times14\times\pi$ is incorrect as $2r$ should be $14$ not $2\times14$.
• Option C: $\frac{7}{2}\times\pi$ is incorrect as it does not match the circumference formula.
• Option D: $14\times\pi$ is correct as it is in the form of $\pi d$ with $d = 14$.
• Option E: $49\times\pi$ is incorrect as it does not match the circumference formula.

Answer:

A. $2\times7\times\pi$, D. $14\times\pi$