If triangle ABC has the following measurements, what is the measure of angle B?

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If triangle ABC has the following measurements, what is the measure of angle B?
a = 5
b = 7
c = 10

Guest May 26, 2015

+130466

+5

Best Answer

Using the Law of Cosines, we have

7^2 = 5^2 + 10^2 - 2(5)(10)cos(B)

cos(B) = (7^2 - 5^2 - 10^2) / (-2(5)(10) )

B = cos^-1 [ (7^2 - 5^2 - 10^2) / (-2(5)(10) ] = cos^-1 (.76) = about 40.54°

CPhill May 26, 2015

CPhill · Answer 1 · 2015-05-26T10:37:13

Using the Law of Cosines, we have

7^2 = 5^2 + 10^2 - 2(5)(10)cos(B)

cos(B) = (7^2 - 5^2 - 10^2) / (-2(5)(10) )

B = cos^-1 [ (7^2 - 5^2 - 10^2) / (-2(5)(10) ] = cos^-1 (.76) = about 40.54°