If the circumference of two circles are in the ratio c1 c2 then the ratio of their areas in

Check out the new look and enjoy easier access to your favorite features

Page 2

Get Access To Our

Free Batches Now

Get instant access to high-quality material

Question 5 Mensuration 2 Exercise 21.1

Answer:

Given that the ratio of the radii = 3: 2

So, let the radii of the two circles be 3r and 2r respectively.

And let C1 and C2 be the circumference of the two circles of radii 3r and 2r respectively.

C1 = 2 × 3 π r = 6 π r … (i)

Now C2 = 2 × 2 π r = 4 π r … (ii)

Consider, C1/C2 = (6 π r)/ 4 π r = 6/4 = 3/2

C1: C2 = 3: 2

Video transcript

"hi guys welcome to lido q a video i am vineet your leader tutor glad to bring you this question on your screen write the decimal expansion of each of the following numbers and say what kind of decimal expansion it has so let us take a look at them one by one so number one is 36 by 100 right so if we divide 36 by 100 clearly we get 0 and point 3 is 300 and then we get 600 so it is so this is equal to 0.36 it is a terminating decimal isn't it guys let us look at number 2 4 1 by 8 can be written as 4 into eight plus one by eight this can be written as 33 by eight so eight fours are 32 point we get 10 here so let's do it eight fours are 32 so we get 10 here point 1 8 then we get 20 here twos are sixteen then we get forty here fives are forty hence zero so four point one two five so it is a terminating decimal right guys let us look at number three so two by nine will be one point right sorry two point two two two two two so it is a non-terminating recurring decimal number 4 is 2 by 11 this is equal to 0.2 sorry 0.1 8 1 8 1 8 so it is a non-terminating recurring decimal these are easy guys aren't they 3 by 13. us look at 3 by 13 3 13 so 13 zeros are zero and then we have 30 point 13 2's are 26 then we have 40 threes are 39 then we have 10 so 0 so 100 so 5 6 7 2 3 0 7 91 then again we have 90 so 2 3 0 7 6 6 78 then we have 120 again nine one one seven then we get so we have zero point two three zero seven six nine again thirty the same thing will repeat so it is a non-terminating recurring decimal if you divide it guys you will see right now let us look at the last one the last one is 6 329 by 400 so let's do the division here 400 329 ones are 329 then we have 710 so point two okay i took that wrong so this would be 329 by 400. so 0's are three two nine zero point eight zero three two zero zero so ninety nine hundred to the eight hundred we have hundred and thousand again twos are eight hundred two hundred thousand fives are two thousand so this is equal to zero point 0.8225 it is a terminating decimal wasn't that easy guys right okay if you still have a doubt please leave a comment below do like the video and subscribe to our channel i'll see you in our next video until then bye kids keep practicing"

If the circumferences of two circles are in the ratio c1: c2, then the ratio of their areas is

Solution