Question

9 sec² A − 9 tan² A = ______.

Options

• 1

• 9

• 8

• 0

Answer 1

9 sec² A − 9 tan² A = 9.

Explanation:

9 sec²A − 9 tan²A

= 9 (sec²A − tan²A)

= 9 (1)           ...[As sec² A − tan² A = 1]

= 9

Hence, alternative 9 is correct.