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  • In triangle ABC, a=2 cm, b=3 cm and  c=4 cm, then angle A equals   Option: 1 <img alt="{\cos ^{-1}\left(\frac{1}{24}\right)}" src

In triangle ABC, a=2 cm, b=3 cm and  c=4 cm, then angle A equals   

Option: 1

{\cos ^{-1}\left(\frac{1}{24}\right)}


Option: 2

\\ {\cos ^{-1}\left(\frac{11}{16}\right)}


Option: 3

\\ {\cos ^{-1}\left(\frac{7}{8}\right)}


Option: 4

\\ {\cos ^{-1}\left(-\frac{1}{4}\right) }


Answers (1)

best_answer

\\\cos A=\frac{b^{2}+c^{2}-a^{2}}{2 b c}\\\\ \cos A=\frac{3^{2}+4^{2}-2^{2}}{2\times 3 \times 4}\\\\ \cos A=\frac{7}{8}\\ A=cos^{-1}\frac{7}{8}

Posted by

Nehul

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