Below are some of the important formulas which will help you in CDSE, only a couple of topics have been covered in this post. Time limit in CDSE is less so the better you know the formulas the faster you will be able to solve your paper.

**Logarithm**

**Trigonometry **

Angle | |||||

SinA | 0 | 1 | |||

CosA | 1 | 0 | |||

TanA | 0 | 1 | Not defined | ||

CosecA | Not defined | 2 | 1 | ||

SecA | 1 | 2 | Not defined | ||

CotA | Not defined | 1 | 0 |

Trigonometric ratios asked in CDS examination.

- for
- for

**Polynomials**

**Arithmetic Progression[AP]**

- The general form of an AP is a, a + d, a + 2d, a + 3d, . . . . Where ‘d’ is called the common difference.
- If a,b, c are in AP, then .
- In an AP with first term ‘a’ and common difference ‘d’, the nth term (or the general term) is given by .
- The sum(S) of the first n terms of an AP is given by, .
- If l is the last term of the finite AP, say the nth term, then the sum of all terms of the AP is given by :.

**Quadratic equation**

- A quadratic equation in the variable x is of the form , where a, b, c are real numbers and a .
- A real number is said to be a root of the quadratic equation , if .
- Quadratic formula: The roots of a quadratic equation are given by , provided .
- A quadratic equation has,
- Two distinct real roots if .
- Two equal roots(i.e coincident roots) if .
- No real roots if .