Question

Find the measure of B and C. Round the measure of angles to the nearest tenth.

B = 40°, C = 81.9°
B = 58.1°, C = 40°
B = 81.9°, C = 58.1°
B = 58.1°, C = 81.9°

Answer 1

Hello,

a=|BC|,b=6,c=7

Theorem of Al Kashi gives :
a²=b²+c²-2bc cos(40°)=6²+7²-2*6*7*cos 40°
==>a=4,5444765...

Law of sinus:
sin 40°/a=sin C/7==>sin C=0,9901059...==>C=81,933535≈81.9°
sin 40/a=sin B/6==>sin B=0,848662...==>B=58,0664649...≈58.1°

Answer D