Question

answer the following questions:

1. which measurement is needed to find the area and perimeter of circle?

a. diameter only \t\t\tc. radius only
b. circumference only \t\t\td. perimeter

1. the radius of a circle is 10 cm. what is its diameter?

a. 2 cm \t\t\tc. 10 cm
b.5 cm \t\t\td. 20 cm

1. which is a correct equation for the circumference of a circle?

a. $a = \frac{4\pi r}{2}$ \t\t\tc. $a = \pi r^2$
b. $c = 2\pi r$ \t\t\td. $c = \pi r^2$

1. what is the perimeter of a circle with diameter of 12 cm?

(use $\pi = 3.14$)

1. what is the area of a circle with a radius of 3 cm?

Explanation:

Step1: Q1: Identify required measure

Area: $A=\pi r^2$, Perimeter (Circumference): $C=2\pi r$ or $C=\pi d$. Radius/diameter works; radius is direct.

Step2: Q2: Calculate diameter from radius

Diameter $d=2r$, $r=10$ cm.
$d=2\times10=20$ cm

Step3: Q3: Match circumference formula

Circumference formula is $C=2\pi r$ or $C=\pi d$.

Step4: Q4: Find perimeter (circumference)

$C=\pi d$, $d=12$ cm, $\pi=3.14$.
$C=3.14\times12=37.68$ cm

Step5: Q5: Calculate circle area

$A=\pi r^2$, $r=3$ cm, $\pi=3.14$.
$A=3.14\times3^2=3.14\times9=28.26$ cm²

Answer:

1. C. Radius only
2. D. 20 cm
3. B. $C=2\pi r$
4. 37.68 cm
5. 28.26 cm²