Which is the positive coterminal angle of ( -780^\circ )?
Answer and explanation
Correct answer: \(300^\circ\)
Coterminal angles differ by an integral multiple of \(360^\circ\). Adding \(3\times360^\circ=1080^\circ\) to \(-780^\circ\) gives \(300^\circ\): \(-780^\circ+1080^\circ=300^\circ\). Hence, \(300^\circ\) is correct. \(240^\circ\) is not coterminal because \(240^\circ-(-780^\circ)=1020^\circ\), which is not a multiple of \(360^\circ\). Exam tip: Keep adding \(360^\circ\) to a negative angle until the least positive angle is obtained.
Frequently asked questions
What is the correct answer to this question?
\(300^\circ\)
Why is this the correct answer?
Coterminal angles differ by an integral multiple of \(360^\circ\). Adding \(3\times360^\circ=1080^\circ\) to \(-780^\circ\) gives \(300^\circ\): \(-780^\circ+1080^\circ=300^\circ\). Hence, \(300^\circ\) is correct. \(240^\circ\) is not coterminal because \(240^\circ-(-780^\circ)=1020^\circ\), which is not a multiple of \(360^\circ\). Exam tip: Keep adding \(360^\circ\) to a negative angle until the least positive angle is obtained.
Which subject and chapter does this question cover?
This is a Class 12 Mathematics question. Chapter: Trigonometric Functions. Topic: Angles.
