Topics
Integers
- Natural Numbers
- Whole Numbers
- Negative and Positive Numbers
- Integers
- Representation of Integers on the Number Line
- Ordering of Integers
- Addition of Integers
- Subtraction of Integers
- Properties of Addition and Subtraction of Integers
- Multiplication of a Positive and a Negative Integers
- Multiplication of Two Negative Integers
- Product of Three Or More Negative Integers
- Closure Property of Multiplication of Integers
- Commutative Property of Multiplication of Integers
- Multiplication of Integers with Zero
- Multiplicative Identity of Integers
- Associative Property of Multiplication of Integers
- Distributive Property of Multiplication of Integers
- Making Multiplication Easier of Integers
- Division of Integers
- Properties of Division of Integers
Fractions and Decimals
- Concept of Fraction
- Types of Fractions
- Concept of Proper and Improper Fractions
- Concept of Mixed Fractions
- Concept of Equivalent Fractions
- Like and Unlike Fraction
- Comparing Fractions
- Addition of Fraction
- Subtraction of Fraction
- Multiplication of a Fraction by a Whole Number
- Using Operator 'Of' with Multiplication and Division
- Multiplication of Fraction
- Division of Fractions
- Concept of Reciprocals or Multiplicative Inverses
- Problems Based on Fraction
- The Decimal Number System
- Comparing Decimal Numbers
- Addition of Decimal Fraction
- Subtraction of Decimal Numbers
- Multiplication of Decimal Numbers
- Division of Decimal Numbers
- Problems Based on Decimal Numbers
Data Handling
Simple Equations
Lines and Angles
The Triangle and Its Properties
- Basic Concepts of Triangles
- Classification of Triangles based on Sides
- Classification of Triangles based on Angles
- Median of a Triangle
- Altitudes of a Triangle
- Exterior Angle of a Triangle and Its Property
- Some Special Types of Triangles - Equilateral and Isosceles Triangles
- Basic Properties of a Triangle
- Right-angled Triangles and Pythagoras Property
Comparing Quantities
- Ratio
- Concept of Equivalent Ratios
- Proportion
- Unitary Method
- Basic Concept of Percentage
- Estimation in Percentages
- Interpreting Percentages
- Conversion between Percentage and Fraction or Decimal
- Ratios to Percents
- Increase Or Decrease as Percent
- Basic Concepts of Profit and Loss
- Profit or Loss as a Percentage
- Calculation of Interest
Congruence of Triangles
- Similarity and Congruency of Figures
- Congruence Among Line Segments
- Congruence of Angles
- Congruence of Triangles
- Criteria for Congruence of Triangles
- Criteria for Similarity of Triangles
- SAS Congruence Criterion
- ASA Congruence Criterion
- RHS Congruence Criterion
- Exceptional Criteria for Congruence of Triangles
Rational Numbers
- Rational Numbers
- Equivalent Rational Number
- Positive and Negative Rational Numbers
- Rational Numbers on a Number Line
- Rational Numbers in Standard Form
- Comparison of Rational Numbers
- Rational Numbers Between Two Rational Numbers
- Addition of Rational Number
- Subtraction of Rational Number
- Multiplication of Rational Numbers
- Division of Rational Numbers
Perimeter and Area
- Basic Concepts in Mensuration
- Concept of Perimeter
- Perimeter of a Rectangle
- Perimeter of Squares
- Perimeter of Triangle
- Perimeter of Polygon
- Concept of Area
- Area of Square
- Area of Rectangle
- Triangles as Parts of Rectangles and Square
- Generalising for Other Congruent Parts of Rectangles
- Area of a Parallelogram
- Area of a Triangle
- Circumference of a Circle
- Area of Circle
- Conversion of Units
- Problems based on Perimeter
- Problems based on Area
Practical Geometry
- Construction of a Line Parallel to a Given Line, Through a Point Not on the Line
- Construction of Triangles
- Constructing a Triangle When the Length of Its Three Sides Are Known (SSS Criterion)
- Constructing a Triangle When the Lengths of Two Sides and the Measure of the Angle Between Them Are Known. (SAS Criterion)
- Constructing a Triangle When the Measures of Two of Its Angles and the Length of the Side Included Between Them is Given. (ASA Criterion)
- Constructing a Right-angled Triangle When the Length of One Leg and Its Hypotenuse Are Given (RHS Criterion)
Algebraic Expressions
Exponents and Powers
- Concept of Exponents
- Multiplying Powers with the Same Base
- Dividing Powers with the Same Base
- Taking Power of a Power
- Multiplying Powers with Different Base and Same Exponents
- Dividing Powers with Different Base and Same Exponents
- Numbers with Exponent Zero, One, Negative Exponents
- Miscellaneous Examples Using the Laws of Exponents
- Decimal Number System Using Exponents and Powers
- Crores
Symmetry
Visualizing Solid Shapes
- Introduction
- Construction 1: Three Sides Given (SSS)
- Construction 2: Two Sides and Included Angle Given (SAS)
- Construction 3: Two Angles and the Included Side Given (ASA)
- Key Points Summary
Introduction
Triangle construction is the process of accurately drawing a triangle using basic geometric tools—a ruler (straightedge), a compass, and often a protractor—when given specific measurements. These measurements are typically side lengths or angle measures.
Construction 1: Three Sides Given (SSS)
Example: Construct triangle ABC with
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AB = 7.6 cm
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AC = 6 cm
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CB = 4 cm
Steps:
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Draw a rough sketch of triangle ABC.
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Draw the base AB = 7.6 cm.
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With A as center, draw an arc of radius 6 cm.
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With B as center, draw another arc of radius 4 cm. Let the arcs intersect at point C.
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Join AC and BC.
Construction 2: Two Sides and Included Angle Given (SAS)
Example: Construct triangle ABC with
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AB = 3 cm
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BC = 5 cm
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∠ABC = 60°
Steps:
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Draw a rough sketch of triangle ABC.
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Draw base BC = 5 cm.
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At point B, use a protractor to construct ∠ABC = 60°.
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With B as the centre, draw an arc of radius 3 cm to locate point A on the 60° line.
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Join AC.
Construction 3: Two Angles and the Included Side Given (ASA)
Example: Construct triangle ABC with
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AB = 4 cm
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∠A = 60°
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∠B = 30°
Steps:
- Draw a rough sketch of triangle ABC.
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Draw the base AB = 4 cm.
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At point A, draw a 60° angle (ray AP).
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At point B, draw a 30° angle (ray BQ).
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The point where ray AP and ray BQ meet is point C.
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Join AC and BC.
Key Points Summary
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The Three Core Rules: Triangles are primarily constructed using the three congruence criteria:
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SSS (Side-Side-Side: Three sides given).
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SAS (Side-Angle-Side: Two sides and the included angle given).
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ASA (Angle-Side-Angle: Two angles and the included side given).
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Planning First: Always begin with a rough sketch to plan the construction steps and visualize the final shape.
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Accuracy is Key: Use your compass, ruler, and protractor carefully to maintain precise measurements throughout the process.
