In this item, we are asked to determine the sides and the angles of the given triangle ABC. We use the cosine law for the first one,
A/cos A = B/cos B
Substituting,
84 / cos 13° = 66/ cos b
The value of b is equal to 40°.
The sum of the measures of the angle in the triangle is equal to 180°
a + b + c = 180°
13 + 40 + c = 180°
c = 127°
Use again Sine Law,
B/ sinb= C / sin c
Substituting,
66/sin 13 = C/sin .
The value of c from the equation is 127.32.
