If an angle is (-675^\circ), what is its principal angle?
Answer and explanation
Correct answer: \(45^\circ\)
To find the principal angle, add a multiple of \(360^\circ\) until the result lies between \(0^\circ\) and \(360^\circ\). Here, \(-675^\circ+720^\circ=45^\circ\), where \(720^\circ=2\times360^\circ\). Therefore, the principal angle is \(45^\circ\). Although \(60^\circ\) is close, it is not coterminal with \(-675^\circ\). Exam tip: for a negative angle, keep adding \(360^\circ\).
Frequently asked questions
What is the correct answer to this question?
\(45^\circ\)
Why is this the correct answer?
To find the principal angle, add a multiple of \(360^\circ\) until the result lies between \(0^\circ\) and \(360^\circ\). Here, \(-675^\circ+720^\circ=45^\circ\), where \(720^\circ=2\times360^\circ\). Therefore, the principal angle is \(45^\circ\). Although \(60^\circ\) is close, it is not coterminal with \(-675^\circ\). Exam tip: for a negative angle, keep adding \(360^\circ\).
Which subject and chapter does this question cover?
This is a Class 12 Mathematics question. Chapter: Trigonometric Functions. Topic: Angles.
