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Geometry Properties for SSC CGL Exams Tier 1, Tier 2

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Geometry Properties for SSC CGL Exams Tier 1, Tier 2

Geometry Properties for SSC CGL Exams Tier 1, Tier 2

In SSC CGL Geometry is considered the most important topic. It contributes around 8-10 marks in Tier 1 math and 16-18 question in Tier 2. It means there is 15-20% role of geometry in SSC CGL math. Out of 8-10 questions 5-6 questions are directly related to properties.

I will cover the geometry portion in 5 articles.

Article 1: Current article: properties of Lines, Angle,Triangle

Article 2: Properties of Quadrilateral , Polygon

Articles 3: Properties of Circle, Concept of Triplet, special points to be noted on geometry

Article 4: 20 Most important Questions on Geometry for SSC CGL

Articles : 21-40 Most Important questions on Geometry for SSC CGL exams.

What does Geometry include?

  • Lines
  • Angles
  • Triangle
  • Quadrilateral
  • Polygon
  • Circle

You may subscribe for regular articles on SSC CGL exam on this website

Let us discuss one by one and start with article 1 i.e. current article. 


AB and CD are two parallel lines. EF is a transverse line .

  • vertically opposite angles are equal e.g. ∠2 = ∠4
  • ∠1 and ∠2 are called adjacent angles
  • ∠1 = ∠5 are called corresponding angles
  • ∠4 = ∠6 are called alternate angles
  • ∠3 + ∠6 =180° are called interior angles. Useful to understand quadrilateral angles.
  • In other words interior angles same side = 2 right angles = 180° = π radians = 1/2 turn
  • Sum of exterior angles same side ∠2 + ∠7 = 180°

Angle Bisector 

Triangle two Types 

Based on sides 

  • Equilateral Triangle : All three sides equal
  • Isosceles Triangle : Two sides equal
  • Scalene Triangle : all three sides different

Based on Angles

  • Right Angle Triangle : One angle 90°
  • Obtuse Angle Triangle : One angle more than 90°
  • Acute Angle Triangle : All angles less than 90°

Congruence of triangles

What is congruence?

When a triangle exactly covers other triangle i.e. mirror image

Triangle are always congruence when

  • SSS : When three sides are equal
  • ASA : When two angles and one side equal
  • SAS : When two sides and one angle  equal.

Then what is similar triangle: 

In case of similarity


  • Each median is split into 1:2
  • Meet at a point G = Centroid

If area of triangle AGE is 24cm2, then area of quadrilateral BDGF would be 48 cm3. 

In fact median AD divides triangle in to equal parts. Also three triangle AGB, AGC, BGC are equal.

If we join EF then area of triangle GEF are alsways equal to 1/12 of triangle ABC.

Important points about triangle:

  • Sum of two sides of a triangle are always greater than third side and difference of two sides of  a triangle is always smaller than third side.