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PLease help me it says use cosine law

PLease help me it says use cosine law-example-1

2 Answers

3 votes

Answer:59

Step-by-step explanation:

C2=a2+b2-2ab cosC

13x13=15x15+6x6-2(15)(6)cosC

169=225+36-180cosC

169=261-180cosC

-92=180cosC

-92/-180=cosC

C=arccos92/180. On your calculator it will say cos-1

C=59.23 or m<B = 59. Rounded to the nearest degree.

User Jonathan Tran
by
3.9k points
3 votes

Answer:

59 degrees

Explanation:

law of cosines states that

for sides A B C and angle c opposite to side C,


C = √(A^2 + B^2-2ABcos(c)) \\cos(c) = (c^2-a^2-b^2)/(-2ab)

cos(b) =
(13^2-6^2-15^2)/(-2(6)(15)) = 23/45

cos-1(23/45) = b

b = 59

User Aidonsnous
by
3.7k points