If the circumference of a circle is 28 π cm then find the value of

Question

C= 28π cm

28π =2×22÷7× r

28×22÷7 = 2×22÷7×r

28×22/7=2×22/7×r

44=44/7×r

44×7= 44×r

308=44×r

r=308/44

R = 7

Answer 1

Hi Inchara,

Topic: Circumference of a circle, C is equal to 2 * π * radius of the circle

I noticed in your work shown that you substituted 22/7 for π. Depending on your teacher's instructions, this may be okay. Overall, I think you did a great job and clearly showed the correct overall process; however, I did note an error on line 5. Let's review below

Your work

Line 1: C= 28π cm

Line 2: 28π =2×22÷7× r

Line 3: 28×22÷7 = 2×22÷7×r

Line 4: 28×22/7=2×22/7×r

Line 5: 44=44/7×r

Looks like you dropped the "*22/7" on the lefthand side of the equation here moving from line 4 to 5, and this changed your ultimate response. I recommend trying again from this step and letting us know what you wind up with.

~david