PLS help. 30 points and brainliest In triangle ABC, a = 3, b = 5, and c = 7. Find the approximate value of angle A.

22°
158°
142°
38°

a^{2} = b^{2} + c^{2} - 2bc\:cosAa2=b2+c2−2bccosA

Add your given values to the equation and simplify:

3^{2} = 5^{2} + 7^{2} -2(5)(7)cosA32=52+72−2(5)(7)cosA

9 = 25 + 49 - 70cosA9=25+49−70cosA

9 - 25 - 49 = -70cosA9−25−49=−70cosA

-65 = -70cosA−65=−70cosA

cosA = \frac{-65}{-70}cosA=−70−65

cosA = \frac{13}{14}cosA=1413

A = cos^{-1}\:\frac{13}{14}A=cos−11413

Use your scientific calculator to evaluate. Round the answer to as many decimal places as the question asks:

A = 21.7867893...\:^{\circ}A=21.7867893...∘

Hope this helped :)

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step-by-step explanation:

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