Posted by Anonymous on .
use sum or difference identities to find the exact value of the trigonometric function: tan 345
please show work, i cant figure out what im doing wrong!

trig 
bobpursley,
tan(345)?
Tan(2*345)=tan(690)=tan(72030)=tan(30)
tan(2*345)= 2*tan(345)/(1tan^2(345)
lets call tan(345) Y
tan(30)=2y/(1y^2)
Call Tan(30) X
xXY^2=2Y
XY^2+2Yx=0
use the quadratic to solve for y in terms of X
(tan(30)=1/sqrt3) 
trig 
mostafa,
prove that tan20 tan30 tan40 = tan 10