Question

Which of the following statements are true for any triangle? Choose all that apply. (3 correct answers)

Answer 1

Tan(x) = sin(x)/cos(x) is one trig identity you should memorize. So one of the answers is choice A. 

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Multiply both sides by cos(x) to get

cos(x)tan(x) = sin(x)
sin(x) = cos(x)tan(x)

Another answer is choice C

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Then we can divide both sides by tan(x) to get

sin(x)/tan(x) = cos(x)
cos(x) = sin(x)/tan(x)

Choice E is another answer.

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In summary the answers are: A, C, E

Answer 2

Try the equation or rule
ab=c
c/b=a
c/a=b