Respuesta :
Answer:
 sin m∠C = 2 square root of 5 all over 5
Step-by-step explanation:
The mnemonic SOH CAH TOA is helpful for sorting this out. A picture can help, too. The mnemonic tells you ...
 Sin = Opposite/Hypotenuse
 Cos = Adjacent/Hypotenuse
Here, the hypotenuse is 3√5. Putting that in the denominator will result in a factor of (√5)/5 in the sine and cosine values. (This eliminates the third choice.)
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We can examine the ratios that are offered in the answer list and see what they really represent:
 (2√5)/5 = AB/BC = sin(C) . . . . not cosine
 (√5)/5 = AC/BC = cos(C) . . . . not sine
 (√5)/2 = BC/AB = 1/sin(C) = csc(C) . . . . not cosine
 (2√5)/5 = AB/BC = sin(C) . . . . . the correct answer choice
