Question

Find the value of 4 cosec square 18- 4 tan square 72

Answer 1

4 cosec² 18° - 4 tan² 72°

==> 4 ( cosec² 18° - tan² 72° )

==> 4 ( cosec² 18° - cot² ( 90° - 18° ) ) [ tan² A = cot² ( 90° -  A ) ]

==> 4 ( cosec² 18° - cot² 18° )

==> 4 × 1 [ cosec² A - cot² A = 1 ]

==> 4

The value is 4

Hope it helps :-)

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Answer 2

Answer:can I know this question is from which textbook?

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