Which property justifies this statement? . r(s + t) = rs + rt. a.. associative. b.. distributive. c.. symmetric. d.. transitive. .

The answer to the question above is letter "B. distributive". The variable r which is multiplied to the quantity of s + r is distributed to the terms inside the parentheses. By distributed we mean to say, multiplied. This gives us the answer of rs + rt. 

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since the cosine is the ratio of the adjacent side to the hypotenuse, you can see that cos 60° = ½. answer. according to the property of cofunctions (topic 3), sin 30° is equal to cos 60°. sin 30° = ½.