Mathematics
Grazyna465
2017-08-23 10:53:30
How to do this step by step?
ANSWERS
emma20
2017-08-23 15:18:35

The cosine rule states  a^2 = b^2 + c^2 - 2bcCOS(A) In this problem  a is directly opposite angle A and therefore is a=101 b = 67 c = 78 therefore  [latex]101 ^2= 67^2 + 78^2 - (2 *67*78cosA)[/latex] Therefore 10201 = 10573 - 10452cosA 10452cosA = 10573 - 10201 10452cosA = 372 cosA = 0,035591.... A = [latex] cos^{-1}( 0.0355912) [/latex] A = 87.96 degrees Therefore A = 88 degrees to 2 significant figures

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