6 Questions
What is the formula to calculate the circumference of a circle?
2 * π * r
What is the relationship between the diameter and the radius of a circle?
The diameter is twice the length of the radius
What is the area of a circle if the radius is 5 units?
25π square units
What is the sum of the interior angles of a circle?
360 degrees
What is the relationship between the circumference and diameter of a circle?
The circumference is pi times the diameter
What is the measure of the central angle that subtends an arc equal in length to the radius of the circle?
90 degrees
Study Notes
Circle Properties
- The circumference of a circle can be calculated using the formula: Circumference = 2 × π × radius
- The diameter of a circle is twice the length of the radius (Diameter = 2 × radius)
- The radius of a circle is half the length of the diameter (Radius = Diameter ÷ 2)
Circle Area
- The area of a circle can be calculated using the formula: Area = π × radius²
- If the radius of a circle is 5 units, the area would be approximately 78.5 square units (Area = π × 5²)
Angles in a Circle
- The sum of the interior angles of a circle is 360 degrees
- A central angle that subtends an arc equal in length to the radius of the circle measures 60 degrees
Test your knowledge of circles with this class 9 CBSE quiz. Answer questions about the circumference formula, the relationship between diameter and radius, and calculate the area of a circle with a given radius.
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