Q25 of 153 Page 7

9 sec2 A − 9 tan2 A is equal to

To find: 9 sec2 A – 9 tan2 A

Consider 9 sec2 A – 9 tan2 A = 9 (sec2 A – tan2 A)


∵ 1 + tan2 A = sec2 A


∴ 9 sec2 A – 9 tan2 A = 9 (sec2 A – tan2 A)


= 9 (1 + tan2 A – tan2 A) = 9

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