Question

Find $f\left(\pi \right)$
(a) $f\left(x\right)=\sin x+\cos x$
(b) $f\left(x\right)=\sin x-\cos x$

Answer 1

a)$f\left(\pi \right)=\sin \pi +\cos \pi 0+(-1)=-1$

b)$f\left(\pi \right)=\sin \pi -\cos \pi 0-(-1)=1$