KnowledgeBoat Logo
|

Mathematics

If cot A + (1cotA)\Big(\dfrac{1}{\cot A}\Big) = 2, then cot2A + (1cot2A)\Big(\dfrac{1}{\cot^2 A}\Big) equals:

  1. 0

  2. 1

  3. 2

  4. 4

Trigonometric Identities

2 Likes

Answer

Given,

cot A + (1cotA)\Big(\dfrac{1}{\cot A}\Big) = 2

Square on both sides,

(cotA+1cotA)2=22cot2A+1cot2A+2=4cot2A+1cot2A=42cot2A+1cot2A=2.\Rightarrow \Big(\cot A + \dfrac{1}{\cot A}\Big)^2 = 2^2 \\[1em] \Rightarrow \cot^2 A + \dfrac{1}{\cot^2 A} + 2 = 4 \\[1em] \Rightarrow \cot^2 A + \dfrac{1}{\cot^2 A} = 4 - 2 \\[1em] \Rightarrow \cot^2 A + \dfrac{1}{\cot^2 A} = 2 .

Hence, option 3 is the correct option.

Answered By

1 Like


Related Questions