# Combined Defence Services (CDS)

## Combined Defence Services (CDS)

The Combined Defence Services Examination is conducted by the Union Public Service Commission for recruitment of Commissioned Officers in the Indian Military Academy, Officers Training Academy, Indian Naval Academy and Indian Air Force Academy.

###### What's Included

- Mobile support
- Lesson archive
- Anytime access

###### Features

- ENGLISH
- GENERAL KNOWLEDGE
- ELEMENTARY MATHEMATICS

###### Requirements

None

## Lessons

- 4 Sections

- ENGLISH
Description

- Spotting of Errors
- Antonyms
- Synonyms
- Vocabulary (Idioms & Phrases)
- Sentence Improvement
- Sentence Completion (Fill in the blanks & Cloze Test)
- Ordering of Words & Sentences
- Comprehension
- Active – Passive Voice
- Direct – Indirect Speech or Reported Speech
- One Word Substitution
- Parts of Speech
- Spelling
- Transformation

- GENERAL KNOWLEDGE
Description

- Physics
- Chemistry
- Biology
- Indian Polity
- History
- Geography
- Economics
- Defence Specific
- Current Affairs & Static GK

- ELEMENTARY MATHEMATICS
Description

**Number System—**Natural numbers, Integers, Rational and Real numbers.Fundamental operations, addition, subtraction, multiplication, division, Square

roots, Decimal fractions. Unitary method, time and distance, time and work,

percentages, applications to simple and compound interest, profit and loss, ratio and

proportion, variation.

**Elementary Number Theory—**Division algorithm. Prime and composite numbers.Tests of divisibility by 2, 3, 4, 5, 9 and 11. Multiples and factors. Factorization

Theorem. H.C.F. and L.C.M. Euclidean algorithm. Logarithms to base 10, laws of

logarithms, use of logarithmic tables.

**ALGEBRA**Basic Operations, simple factors, Remainder Theorem, H.C.F., L.C.M., Theory of

polynomials, solutions of quadratic equations, relation between its roots and

coefficients (Only real roots to be considered). Simultaneous linear equations in two

unknowns—analytical and graphical solutions. Simultaneous linear inequations in

two variables and their solutions. Practical problems leading to two simultaneous

linear equations or inequations in two variables or quadratic equations in one 21

variable & their solutions. Set language and set notation, Rational expressions and

conditional identities, Laws of indices.

**TRIGONOMETRY**Sine ×, cosine ×, Tangent × when 0° < × < 90° Values of sin ×, cos × and tan ×, for ×

= 0°, 30°, 45°, 60° and 90°

Simple trigonometric identities.

Use of trigonometric tables.

Simple cases of heights and distances.

**GEOMETRY**Lines and angles, Plane and plane figures, Theorems on (i) Properties of angles at

a point, (ii) Parallel lines, (iii) Sides and angles of a triangle, (iv) Congruency of

triangles, (v) Similar triangles, (vi) Concurrence of medians and altitudes, (vii)

Properties of angles, sides and diagonals of a parallelogram, rectangle and square,

(viii) Circles and its properties including tangents and normals, (ix) Loci.

**MENSURATION**Areas of squares, rectangles, parallelograms, triangle and circle. Areas of figures

which can be split up into these figures (Field Book), Surface area and volume of

cuboids, lateral surface and volume of right circular cones and cylinders, surface

area and volume of spheres.

**STATISTICS**Collection and tabulation of statistical data, Graphical representation frequency

polygons, histograms, bar charts, pie charts etc. Measures of central tendency.