Trigonometric Equations Question 232
Question: In $ \Delta ABC $ , if $ \angle C=90^{o} $ , $ \angle A=30^{o} $ , $ c=20 $ , then the values of a and b are
Options:
A) 10, 10
B) $ 10,,10\sqrt{3} $
C) $ 5,5\sqrt{3} $
D) $ 8,8\sqrt{3} $
Show Answer
Answer:
Correct Answer: B
Solution:
- $ \angle C=90^{o},\angle A=30^{o},c=20, $ then $ a=\frac{c\sin A}{\sin C}=10 $ and $ b=\frac{c\sin B}{\sin C}=10\sqrt{3} $ . Trick: Since the angles are $ 30^{o},60^{o},90^{o} $ , therefore sides must be $ 1:\sqrt{3}:2 $ . Hence $ a=10,b=10\sqrt{3} $ .
BETA
