A student solved for the radius of a circle with a circumference of 12π

Step 1: C = 2 pi r. Step 2: 12 pi = 2 pi r. Step 3: StartFraction 12 pi over 2 pi EndFraction = StartFraction 2 pi r over 2 pi EndFraction. Step 4: 6 = pi r. Step 5: StartFraction 6 over pi EndFraction = StartFraction pi r over pi EndFraction. Step 6: Solving for r, the length of the radius is StartFraction 6 over pi EndFraction centimeters. in which stept did he made the error

Question

Mathematics

Raina Walls

4 January, 19:29

A student solved for the radius of a circle with a circumference of 12π

Step 1: C = 2 pi r. Step 2: 12 pi = 2 pi r. Step 3: StartFraction 12 pi over 2 pi EndFraction = StartFraction 2 pi r over 2 pi EndFraction. Step 4: 6 = pi r. Step 5: StartFraction 6 over pi EndFraction = StartFraction pi r over pi EndFraction. Step 6: Solving for r, the length of the radius is StartFraction 6 over pi EndFraction centimeters. in which stept did he made the error

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Answers (1)

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Bronson Malone · Answer 1

Step 4 is incorrect he did not divide correctly from step3 to step 4

Step-by-step explanation:

The circumference of a circle is

C = 2 * pi * r

We know the circumference is 12 pi

12pi = 2 pi * r

Divide each side by 2 pi

12 pi/2pi = 2pi r / 2pi

6 = r

From step 3 The student did not cancel the pi in the top and the bottom on the right hand side to isolate r

In step 4 he got 6 = pi r instead of pi