Answer
(a). $ a^{2} - 5a + 6$
(b). $ \sin^{2}\theta - 5\sin\theta + 6$
Work Step by Step
(a). Given expression is-
$ (a-2) (a-3)$
= $ a^{2} -3a - 2a +6$
( By FOIL method)
= $ a^{2} - 5a + 6$
(b). Given expression is-
$ (\sin\theta-2) (\sin\theta-3)$
= $ \sin^{2}\theta -3\sin\theta - 2\sin\theta +6$
( By FOIL method)
= $ \sin^{2}\theta - 5\sin\theta + 6$
