2021-06-14

In triangle ABC, $a=15$, $b=14$, $c=10$. Find $m

yunitsiL

The given case is SSS (three sides) so use the Law of Cosines: ${b}^{2}={a}^{2}+{c}^{2}-2a\mathcal{o}sB$
Solve for B.
$2a\mathcal{o}sB={a}^{2}+{c}^{2}-{b}^{2}$
$\mathrm{cos}B=\frac{{a}^{2}+{c}^{2}-{b}^{2}}{2}ac$
$m
$m
$m
Use a calculator in DEGREE mode: $m\angle B\approx 64.5°$

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