Answer
a) $ b-a $
b) $\dfrac{a-1}{b}$
Work Step by Step
a) $\sin (- \theta) +\cos (-\theta) =-\sin \theta+\cos \theta $
or, $=-a+b $
or, $=b-a $
b) $\tan (\theta) -\sec (\theta) =\dfrac{\sin \theta}{\cos \theta}-\dfrac{1}{\cos \theta} $
or, $=\dfrac{\sin \theta-1}{\cos \theta}$
or, $=\dfrac{a-1}{b}$
