40 cm = ____ mm what is the answer
2 answers:
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Answer:
<u>Step-by-step explanation:</u>
Note the following identities: tan² x = sec²x - 1
tan² x + sec x = 1
(sec² x -1) + sec x = 1
sec² x + sec x - 2 = 0
(sec x + 2)(sec x - 1) = 0
sec x + 2 = 0 sec x - 1 = 0
sec x = -2 sec x = 1