If pi/2 < x < pi and sin x = 2/3, find sin 2x
E edwerg New member Joined Aug 25, 2005 Messages 4 Aug 25, 2005 #1 If pi/2 < x < pi and sin x = 2/3, find sin 2x
pka Elite Member Joined Jan 29, 2005 Messages 11,983 Aug 25, 2005 #2 You know that cos<SUP>2</SUP>(x)=1−sin<SUP>2</SUP>(x). You also know that cos(x)<0 because pi/2 < x < pi. Use the fact sin(2x)=2sin(x)cos(x).
You know that cos<SUP>2</SUP>(x)=1−sin<SUP>2</SUP>(x). You also know that cos(x)<0 because pi/2 < x < pi. Use the fact sin(2x)=2sin(x)cos(x).
