Posted by nadia on Saturday, November 10, 2012 at 6:13pm.
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(2π-π/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.
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