Use the Cosine Rule
q^2 = 20^2 + 30^2 - 2^20*30 cos 15
= 140.89
so q = sqrt 140.89 = 11.9 (answer)
Answer:

Step-by-step explanation:






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Same sign- <span> keep the </span>same sign<span> and </span>add<span> the absolute value of each number.
different signs- </span><span>keep the </span>sign<span> of the number with the largest absolute value and subtract the smallest absolute value from the largest.</span>