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3 years ago

In △ABC,a=11 , b=20 , and c=28 . Find m∠A .

Mathematics

1 answer:

Helga [31]3 years ago

4 0

Answer:

18.4°

Step-by-step explanation:

Use law of cosine.

a² = b² + c² − 2bc cos A

11² = 20² + 28² − 2(20)(28) cos A

121 = 1184 − 1120 cos A

cos A = 0.949

A = 18.4°

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