## Algebra 2 (1st Edition)

Since $\cos(180-theta)=-\cos \theta$ we obtain $\cos(180-135)=-\cos 135\\\cos 45=-\cos 135\\-\cos 45=\cos 135\\\cos 135=-\frac{\sqrt 2}{2}$ Now find $\sec135=\frac{1}{\cos 135}=\frac{1}{-\frac{\sqrt 2}{2}}=-\frac{2}{\sqrt 2}=-\sqrt 2$