MathematicsChapter 6: Analytical Geometry
General Equation of A Circle
x^2+y^2+Dx+Ey+F=0 represents a real circle when the computed radius squared is positive.
Learning objectives
- State the rule for general equation of a circle.
- Solve a general equation of a circle problem step by step.
- Check the result, restrictions, notation, and units.
Definition
x^2+y^2+Dx+Ey+F=0 represents a real circle when the computed radius squared is positive.
Formula
F=0 represents a real circle when the comp
Where / symbols
- General equation of a circle
- x^2+y^2+Dx+Ey+F=0 represents a real circle when the computed radius squared is positive.
CONCEPT AND RULE
x^2+y^2+Dx+Ey+F=0 represents a real circle when the computed radius squared is positive.
METHOD
For general equation of a circle, identify the given information and required result. Select the matching definition or formula, state its conditions, substitute carefully, simplify one line at a time, and check.
WORKED EXAMPLE
Centre is (-D/2,-E/2).
COMMON MISTAKE
Write the governing rule before substitution, keep brackets and signs visible, and check that the answer satisfies all domain or interval conditions.
How to solve general equation of a circle
- Identify the mathematical objects, givens, restrictions, and required result.
- Choose and write the relevant definition, theorem, or formula.
- Substitute with brackets and carry out one justified step per line.
- Simplify, state the final answer clearly, and verify it in the original setting.
Worked example
- Worked example:
- Centre is (-D/2,-E/2).
In simple words
Write the governing rule before substitution, keep brackets and signs visible, and check that the answer satisfies all domain or interval conditions.
Key points
- General equation of a circle
- rule
- worked example
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.General Equation of A Circle
Sticky Notes · Formula and Worked Revision
Core Idea
- x^2+y^2+Dx+Ey+F=0 represents a real circle when the computed radius squared is positive.
Rule / Formula
- x^2+y^2+Dx+Ey+F=0 represents a real circle when the computed radius squared is positive.
Method
- Identify givens and restrictions.
- Write the rule.
- Substitute and simplify.
- Check the result.
Worked Example
- Centre is (-D/2,-E/2).
Common Error
- Write the governing rule before substitution, keep brackets and signs visible, and check that the answer satisfies all domain or interval conditions.
FBISE Exam Tip
- Show the formula, substitutions, algebra, restrictions, and final answer; method marks need visible reasoning.
60-second revision
- x^2+y^2+Dx+Ey+F=0 represents a real circle when the computed radius squared is positive.
- Worked pattern: Centre is (-D/2,-E/2).
- Final check: domain, sign, notation, units, and reasonableness.
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