9a^2+6a+1-4b^2=(3a+1)^2-(2b)^2=(3a+1-2b)*(3a+1+2b).
Ответ:
tg a + sin a/ tg a= cos a (tg a + sin a)/sin a= cos a(sin a/cos a + cos a * sin a/ cos a)/sin a= cos a( sin a + cos a * sin a/cos a)/sin a= sin a (1+ cos a)/ sin a= 1+ cos a
= (7t - t - p)(7t + t + p) =
= (6t - p)(8t + p)