A triangle has sides A, B, and C. The angle between sides A and B is (pi)/4. If side C has a length of 15 and the angle between sides B and C is ( 3 pi)/8, what are the lengths of sides A and B?

1 Answer
Mar 26, 2018

color(blue)(a = b = (c * sin A) / sin C) = color(blue)(19.6 " units"

Explanation:

To find sides a, b.

Given : hat A = (3pi)/8, hat C = pi/4, c = 15

hat B = pi - (3pi)/8 - pi/4 = (3pi)/8

It's an isosceles triangle with sides angles hatA & hatB = (3pi)/8

![http://www.dummies.com/education/math/trigonometry/laws-of-sines-and-cosines/](useruploads.socratic.org)

Applying Law of Sines,

color(blue)(a = b = (c * sin A) / sin C) = (15 * ((3pi)/8)) / sin (pi/4) = color(blue)(19.6 " units"