I think i know the answer to that question. just wait for a sec.
Step-by-step explanation:
Subtracting equation (2) from equation (1)
Substituting d = - 3 in equation (1), we find:
Hence, first term is zero.
Answer:
AC = 12.38 cm
Step-by-step explanation:
When there are 2 pairs given, we can use the sine rule to solve the problem.
By pairs we mean "an angle and side opposite to it"
<em>1 pair is 85.2 degree angle and 13 cm, and another pair is 71.6 degree angle and the side AC (which we want to figure out).</em>
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Sine Rule is given by 
where,
A and B are the two respective angles and a and b are the two respective sides (of the pairs). Plugging all the info and using algebra, we have:

Thus, AC = 12.38 cm