72 A B This problem refers to triangle ABC If a 39 cm b 11 c

7.2

This problem refers to triangle ABC. If a 39 cm, b 11 cm, and c 31 cm, find the largest angle. (Round your answer to the nearest whole number.)

a=408, c=343m,B=147.5 degree

using cosine law which is

b^2=a^2 + c^2 -2ac cos B

b^2= 408^2 + 343^2 -2(408)(343)cos 147.5

b^2= 166464+117649 +236055.145

b=721m

using sine law

sinB/b=sinA/a

sin147.5/721=sinA/408

sinA=408sin147.5/721

A=17.7 degree

C=180-(A+B)=14.8 degree