Gujarat BoardEnglish MediumSTD 12 ScienceMathsINVERSE TRIGNOMETRIC FUNCTIONS2 Marks
Question
Write the value of $\cos^{-1}(\cos1540^\circ).$
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Answer
We know that $\cos^{-1}(\cos\text{x})=\text{x}$ Now, $\cos^{-1}(\cos1540^\circ)=\cos^{-1}\{\cos(1440+100^\circ)\}$ $=\cos^{-1}\{\cos(100^\circ)\}$$[\because\ \cos(4\pi+100^\circ)=\cos100^\circ]$ $=100^\circ$
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