SOLUTION: 1. If sin x=1/√5,and cos x is less than 0, find sin 2x.

Algebra ->  Trigonometry-basics -> SOLUTION: 1. If sin x=1/√5,and cos x is less than 0, find sin 2x.       Log On


   

Question 702688: 1. If sin x=1/√5,and cos x is less than 0, find sin 2x.
Answer by sachi(548) About Me  (Show Source):
You can put this solution on YOUR website!
If sin x=1/√5,
and cos x =sqrt(1-sin^2x)=sqrt(1-1/5)=+/- 2/√5 is less than 0
so cos x =- 2/√5
sin 2x=2 sinx cosx=2*1/√5*2/√5=2/5
ans