Respuesta :
Consider a triangle ΔABC, where sides AB, BC and angle ∡C are given.
Angle ∡C is the angle opposite of side AB.
It says that the given side opposite the given angle is less than the other given side. It means AB < BC.
It says that the ratio of the longer side to the shorter side, multiplied by the sine of the angle opposite the shorter side, is less than 1. It means
[tex] \frac{BC}{AB} [/tex] · sin(C) < 1
We know about Law of Sines of Triangle is given by :-
[tex] \frac{AB}{sin(C)} =\frac{BC}{sin(A)} =\frac{AC}{sin(B)} \\\\
Solving \;\;\frac{AB}{sin(C)} =\frac{BC}{sin(A)} \\\\
Cross\;\; Multiplying\\\\
AB\; sin(A)=BC\; sin(C)\\\\
sin(A)=\frac{BC}{AB}\; sin(C)\\\\
sin(A) <1 [/tex]\\
We got sin(A) < 1, and BC > AB.
Therefore, angle ∡A could be either acute or obtuse angle.
So, There will be two solutions for the angle ∡A.
⇒ option D is the final answer.
Answer:
(D)
Step-by-step explanation:
Consider a triangle ΔABC, in which sides AB, BC and angle ∠C are given.
Now, according to the question, Angle C is the angle opposite of side AB.
And, the given side opposite the given angle is less than the other given side. that is AB < BC.
Also, it is given that the ratio of the longer side to the shorter side, multiplied by the sine of the angle opposite the shorter side, is less than 1, that is
[tex](\frac{BC}{AB})SinC<1[/tex] (1)
Now, Law of Sines of Triangle, we get
[tex]\frac{AB}{sinC}=\frac{BC}{sinA}=\frac{AC}{sinB}[/tex]
Taking the first and second equality, we have
[tex]\frac{AB}{sinC}=\frac{BC}{sinA}[/tex]
⇒[tex]ABsinA=BCsinC[/tex]
⇒[tex]sinA=\frac{BC}{AB}sinC[/tex]
Using equation (1),we get
[tex]sinA<1[/tex]
Therefore, BC > AB
Hence, angle A could be either acute or obtuse angle.
Therefore, There will be two solutions for the angle A making option D correct.
