In triangle ABC, a = 9, c = 5, and B = 120°. Find b2.6183.5128.5151
Accepted Solution
A:
Answer:The correct answer is 151.Step-by-step explanation:Given,In triangle ABC,BC = a = 9 unit,AB = c = 5 unit,m∠B = 120°,We have to find : b² or AC²,By the cosine law,[tex]b^2=a^2+c^2-2ac cosB[/tex][tex]=9^2+5^2-2\times 9\times 5\times cos 120^{\circ}[/tex][tex]=81+25-90\times -0.5[/tex][tex]=81+25+45[/tex][tex]=151[/tex]Hence, the value of [tex]b^2[/tex] is 151.