Chapter 12 · Class 9 ICSE · Formula Sheet

Circles Formulas — Class 9 ICSE

Explore circle properties including chords, arcs, angles subtended, and cyclic quadrilaterals.

Key Formulas

Equal Chords

\text{Equal chords are equidistant from centre}

Angle at Centre

\text{Angle at centre} = 2 \times \text{Angle at circumference}

Angle in Semicircle

90°

Cyclic Quadrilateral

\text{Opposite angles are supplementary}

Worked Examples

1Using: Area of Circle

Find the area of a circle with radius 7 cm.

Step 1: Area = pi x r^2

Step 2: = 22/7 x 49 = 154 sq. cm.

Answer: 154 sq. cm

2Using: Circumference

Find the circumference of a circle with radius 14 cm.

Step 1: C = 2 x pi x r

Step 2: = 2 x 22/7 x 14 = 88 cm.

Answer: 88 cm

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More Class 9 ICSE Formulas

Rational & Irrational Numbers Compound Interest Expansions Factorization Simultaneous Linear Equations Indices (Exponents)

Frequently Asked Questions

How many formulas are in Class 9 ICSE Circles?+

There are 4 formulas in the Circles chapter for Class 9 ICSE. Each formula is essential for solving problems in this topic.

How to remember Circles formulas easily?+

Practice regularly with worked examples, group related formulas together, and use SparkEd's interactive practice mode to reinforce your memory through problem-solving.

Are these Circles formulas enough for exams?+

Yes, these formulas cover the complete ICSE Class 9 syllabus for Circles. Practice applying them to different types of questions for full exam readiness.

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