If (\tan x+\cot x=5), what is the value of (\tan^2 x+\cot^2 x)?
Answer and explanation
Correct answer: 23
Given \(\tan x+\cot x=5\). Squaring both sides gives \((\tan x+\cot x)^2=\tan^2x+\cot^2x+2\tan x\cot x\). Since \(\tan x\cot x=1\), we get \(25=\tan^2x+\cot^2x+2\). Hence, \(\tan^2x+\cot^2x=23\). Option 25 is only the square of the given sum; the extra 2 must be subtracted. Exam tip: always use \(\tan x\cot x=1\) in such identities.
Frequently asked questions
What is the correct answer to this question?
23
Why is this the correct answer?
Given \(\tan x+\cot x=5\). Squaring both sides gives \((\tan x+\cot x)^2=\tan^2x+\cot^2x+2\tan x\cot x\). Since \(\tan x\cot x=1\), we get \(25=\tan^2x+\cot^2x+2\). Hence, \(\tan^2x+\cot^2x=23\). Option 25 is only the square of the given sum; the extra 2 must be subtracted. Exam tip: always use \(\tan x\cot x=1\) in such identities.
Which subject and chapter does this question cover?
This is a Class 12 Mathematics question. Chapter: Trigonometric Functions. Topic: Trigonometric functions and their properties.
