What is the range of the function (1-\cos x)?
Answer and explanation
Correct answer: \([0,2]\)
Since \(\cos x\) lies in \([-1,1]\), the minimum value of \(1-\cos x\) is \(0\) when \(\cos x=1\), and its maximum value is \(2\) when \(\cos x=-1\). Hence, the range is \([0,2]\). The interval \([-1,1]\) is the range of \(\cos x\), not of \(1-\cos x\). Exam tip: for an expression such as \(a-\cos x\), substitute the endpoint values \(-1\) and \(1\) of \(\cos x\).
Frequently asked questions
What is the correct answer to this question?
\([0,2]\)
Why is this the correct answer?
Since \(\cos x\) lies in \([-1,1]\), the minimum value of \(1-\cos x\) is \(0\) when \(\cos x=1\), and its maximum value is \(2\) when \(\cos x=-1\). Hence, the range is \([0,2]\). The interval \([-1,1]\) is the range of \(\cos x\), not of \(1-\cos x\). Exam tip: for an expression such as \(a-\cos x\), substitute the endpoint values \(-1\) and \(1\) of \(\cos x\).
Which subject and chapter does this question cover?
This is a Class 12 Mathematics question. Chapter: Trigonometric Functions. Topic: Trigonometric functions and their properties.
