Answer:
(D) [tex]b^2=151[/tex]
Step-by-step explanation:
Given: In triangle ABC, a=9, c=5 and ∠B=120°.
To find: The value of [tex]b^2[/tex].
solution: It is given that In triangle ABC, a=9, c=5 and ∠B=120°.
Now, using the law of cosines, we get
[tex]b^2=a^2+c^2-2(a)(c)cosB[/tex]
Substituting the given values, we get
[tex]b^2=9^2+5^2-2(9)(5)cosB[/tex]
[tex]b^2=81+25-90(\frac{-1}{2})[/tex]
[tex]b^2=81+25+45[/tex]
[tex]b^2=151[/tex]
which is the required value of [tex]b^2[/tex].
Therefore, option D is correct.
