Saved Bookmarks
| 1. |
If 2sin^2theta-cos^2theta=2,find theta. |
| Answer» Given:\xa0{tex}2sin^2\\theta-cos^2\\theta=2{/tex}⇒\xa0{tex}2(1-cos^2\\theta)-cos^2\\theta=2{/tex}\xa0{tex}[\\because sin^2\\theta+cos^2\\theta=1]{/tex}⇒{tex}2-2cos^2\\theta-cos^2\\theta=2{/tex}{tex}\\Rightarrow 2-3cos^2\\theta=2{/tex}{tex}\\Rightarrow -3cos^2\\theta=2-2{/tex}⇒\xa0{tex}-3cos^2\\theta=0{/tex}{tex}\\Rightarrow cos^2\\theta=0{/tex}{tex}\\Rightarrow cos\\theta=0{/tex}{tex}\\Rightarrow cos\\theta=cos90°{/tex}{tex}\\Rightarrow \\theta=90°{/tex}{tex}{/tex} | |