Step-2

Title: Circles

Grade: 8-a Lesson: S3-L1

Explanation: Hello Students, time to practice and review the steps for the problem.

Lesson Steps

Step Type Explanation Answer

1

Problem

The circumference of a circle is equal to its area. Find the diameter of the circle.

2

Step

Given

circumference is equal area

3

Formula:

Area of a circle

\$ A = πr^2\$

4

Formula:

Circumference is equal to the area

C = πd

5

Hint

Diameter is twice the length of the radius

d = 2r
\$r = d/2\$

6

Step

Substitute the value in area formula
[∵ Circumference of a circle = Area of a circle]

\$πd = π (d/2)^2\$

7

Step

After simplification

\$πd = π(d^2/4)\$

8

Step

After simply the equation

\$4\cancelπd = \cancelπd^2\$

\$4d = d^2\$ ( \$d^2 = d \times d\$)

\$4\cancel d = \cancel d \times d\$

d = 4

9

Step

After simplification

d = 4 units

10

Step

Therefore, the diameter of the circle is 4 units.

11

SumUp

Can you summarize what you’ve understood in the above steps?

12

Choice.A

This is incorrect because it is not a solution to the quadratic equation

2 units

13

Choice.B

This is incorrect because it is not a solution to the quadratic equation

5 units

14

Choice.C

This is correct. It satisfies both the equation and the physical context of a circle’s diameter is d = 4

4 units

15

Choice.D

This is incorrect because it is not a solution to the quadratic equation

6 units

16

Answer

Option

C

17

SumUp

Can you summarize what you’ve understood in the above steps?


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