A triangle has sides A, B, and C. The angle between sides A and B is pi/4 and the angle between sides B and C is pi/12. If side B has a length of 9, what is the area of the triangle?

1 Answer
Apr 8, 2018

color(green)("Area of Triangle " color(maroon)(A_t = 8.56 color(green)(" sq units")

Explanation:

![https://www.teacherspayteachers.com/Product/Law-of-Sine-and-Law-of-Cosine-Foldable-For-Oblique-Triangles-716112](useruploads.socratic.org)

hat A = pi/12, hat C = pi/4, b = 9

hat B = pi - pi/12 - pi/4 = (2pi)/3

Applying the law of sines,

a = (b * sin A) / sin B = (9 * sin (pi/12)) / sin ((2pi)/3) = 2.69#

Area of triangle, known two sides and the included angle is

A_t = (1/2) a b sin C = (1/2) * 2.69 * 9 * sin (pi/4) = 8.56