A) 12
B) 13
C) 14
D) 15
Correct Answer: B
Solution :
\[{{a}^{2}}={{b}^{2}}+{{c}^{2}}-2bc\cos A\]Þ \[{{a}^{2}}\]\[={{(20)}^{2}}+{{(21)}^{2}}-2.20.21.\frac{4}{5}=169\] Þ \[a=13.\]You need to login to perform this action.
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