Given a triangle $$ △ABC $$ with $$ AC=15 $$ , $$ BC=7 $$ and
$$ ∠ACB=60 $$ , find the value of $$ AB $$ .

Question

Given a triangle $$ △ABC $$ with $$ AC=15 $$ , $$ BC=7 $$ and 
$$ ∠ACB=60 $$ ,  find the value of $$ AB $$ .

Uniteasy Admin · Accepted Answer

Using the Law of Cosines
$$ c^2=a^2+b^2-2ab\cos C $$
$$ c^2 = 15^2+7^2-2	imes 15	imes 7\cos 60\degree $$
$$ c^2 = 15^2+7^2- 15	imes 7 $$
$$ =15	imes 8+49 $$
$$ =169 $$
$$ 	herefore c = 13 $$

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