SOLUTION: If sin theta=3/10,theta in quadrant II,find the exact value of (a)cos theta (b)sin(theta+pi/6) (c)cos(theta-pi/3) (d)tan(theta+pi/4) Help me please!!!

Algebra ->  Trigonometry-basics -> SOLUTION: If sin theta=3/10,theta in quadrant II,find the exact value of (a)cos theta (b)sin(theta+pi/6) (c)cos(theta-pi/3) (d)tan(theta+pi/4) Help me please!!!      Log On


   

Question 955814: If sin theta=3/10,theta in quadrant II,find the exact value of
(a)cos theta (b)sin(theta+pi/6) (c)cos(theta-pi/3) (d)tan(theta+pi/4)
Help me please!!!
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
If sin theta=3/10,theta in quadrant II,find the exact value of
(a)cos theta
cos%5E2%28t%29+%2B+sin%5E2%28t%29+=+1 for all angles
--> cos%28t%29+=+sqrt%281+-+sin%5E2%28t%29%29
cosine is negative in Q2
--------------------------
(b)sin(theta+pi/6)
sin(A+B) = sin(A)cos(B) + sin(B)cos(A)
----------------
(c)cos(theta-pi/3)
Look up "half angle formulas" on Wikipedia.
It's explained in detail there.
(d)tan(theta+pi/4)
tan = sin/cos
Look up "half angle formulas" on Wikipedia.
It's explained in detail there.