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Pi
Definition Of Pi
The ratio of the circumference of a circle to its diameter is known as "Pi".
More About Pi
The 16th letter of the Greek alphabet.
It is symbolically represented as π.
The value of pi is 
or approximately equal to 3.14159.
Pi is an irrational number.
Examples of Pi
According to the definition, Pi = Circumference/Diameter which is shown in the figure i.e. π = C/d, where C is the circumference of the circle and d is its diameter.
Video Examples: What is the Meaning of Pi
Solved Example on Pi
Ques: Find the circumference of the circle.
Choices:
A. 14π cm
B. 16π cm
C. 18π cm
D. 20π cm
Correct Answer: C
Solution:
Step 1: Circumference is the distance around a circle.
Step 2: Circumference of a circle = diameter × π. [Formula.]
Step 3: = 18 × π [Substitute the value.]
Step 4: = 18π [Multiply.]
Step 5: So, the circumference of the circle is 18π cm.