Question

What is the product of:
(2 secQ-3cotQ)(2secQ+3cotQ)

Answer 1

Answer:

(2 secQ- 3 cotQ)(2 secQ+3 cotQ)

using a²-b²=(a-b)(a+b)

(2 secQ)²-(3 cotQ)²

4 sec²Q-9 cot²Q

using cot² theta=sec²theta -1

4sec²Q-9(sec²Q-1)

4sec²Q-9sec²Q-9

-5sec²Q-9

-(5sec²Q+9)