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4 votes

in triangle ABC, AB=7, BC=10, and the measure of angle B=80, to the nearest 10th, what is b

1 Answer

4 votes

Answer:

b = 11.0

Explanation:

From the given properties of the triangle,

b = AC

Applying the cosine rule, we have;


b^(2) =
a^(2) +
c^(2) - 2acCos B

=
10^(2) +
7^(2) - 2(10 x 7) Cos 80

= 100 + 49 - 140 x 0.17365

= 149 - 24.311

= 124.689

b =
√(124.689)

= 11.1664

b = 11.0

User Bill Ruppert
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