Trigonometric Equations Question 230
Question: In a $ \Delta ABC $ , if $ \angle C=30^{o} $ , $ a=47cm $ and $ b=94 $ cm, then the triangle is
[MP PET 1986]
Options:
A) Right angled
B) Right angled isosceles
C) Isosceles
D) Obtuse angled
Show Answer
Answer:
Correct Answer: D
Solution:
- $ \cos C=\frac{a^{2}+b^{2}-c^{2}}{2ab} $
Þ $ \frac{\sqrt{3}}{2}=\frac{{{(47)}^{2}}+{{(94)}^{2}}-c^{2}}{2\times 47\times 94} $
$ \Rightarrow c=58.24 $ $ \angle B=124^{o} $ . Hence obtuse angled triangle.
BETA
