Posted by nadia on Saturday, November 10, 2012 at 6:13pm.
write and that is equivalent to each of the following expression,using the related acute angle
a) sin 13pi/6 b) cos 11pi/8
c) tan 7pi/4

Advance fuctions  Reiny, Saturday, November 10, 2012 at 6:40pm
a) sin(13π/6)
= sin(2π + π/6)
so we are in quadrant I with an angle of sin π/6
sin π/6 = 1/2
cos(11π/6)
= cos(2ππ/6) .... ( think: 330° = 360°  30°)
so we are in quad IV and in IV the cosine is positive
= cos π/6 = √3/2
c) tan 7π/4
= tan (2π  π/4)  in IV where the tangent is negative
= tan π/4 = 1
You can and should check your answers with a calculator.