Chapter 1

NCERT
Class 9
Mathematics
Solutions
3. Recall, π is defined as the ratio of the circumference (say c) of a circle to its diameter (say d). That is, π = c/d . This seems to contradict the fact that π is irrational. How will you resolve this contradiction ?

Question:

Recall, π is defined as the ratio of the circumference (say c) of a circle to its diameter (say d). That is, π = c/d . This seems to contradict the fact that π is irrational. How will you resolve this contradiction ?

Answer:

We often take 22/7 as an approximate value for π. So, π is an irrational number.

∴ π = 22/7 (approx), which is irrational.

c/d = 22/7 (approx), which is irrational.

∵ [π = c/d]

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