SOLUTION: if cos x = 1/9 and x is an obtuse angle, find sin 1/2 x

SOLUTION: if cos x = 1/9 and x is an obtuse angle, find sin 1/2 x

Algebra.Com

Question 843989: if cos x = 1/9 and x is an obtuse angle, find sin 1/2 x
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
if cos x = 1/9 and x is an obtuse angle, find sin 1/2 x

sin(1/2)x=2/3 (in quadrant II where sin>0)
calculator check:
cos(x)=1/9 (in quadrant IV)
x=360-83.62≈276.38˚
x/2≈138.19˚
sin(x/2)=sin(138.19)≈0.6666..≈2/3

RELATED QUESTIONS
Theta = x If x is an acute angle with cos x = 1/9, find the exact value of sin... (answered by Nate,stanbon)

A is an obtuse angle such that cos(A)=-4/5. Find: 1. Cos(4A). 2. Sin... (answered by Edwin McCravy,Alan3354)

If x is an acute angle and sin 2x = a find sin x + cos... (answered by stanbon)

If sin x = -(4/5) and x is in quadrant IV, find cos (1/2)... (answered by lwsshak3)

1. If sin x=1/√5,and cos x is less than 0, find sin 2x. (answered by sachi)

How to find a value of tan x without using calculator if x is obtuse angle and... (answered by Solver92311)

Prove sin^2 x /cos x +sec x =sin x /cot x +1 /cos x is an identity. (answered by MathLover1)

Prove that each is an identity (sin 2 x + sin x)/ (cos 2 x + cos x + 1) = tan... (answered by lwsshak3)

Verify following is an identity... (answered by Tatiana_Stebko)