Question 1162405: Solve each equation to the nearest tenth. Use the given restriction:
cos Θ = -0.25 for 180°<Θ<270° Answer by Theo(13342) (Show Source):
You can put this solution on YOUR website! arc cosine (.25) = 75.52248781 degrees.
that's the reference angle.
notice i looked for arc cosine (plus .25) and not arc cosine (minus .25)
the positive trig function will always find you the reference angle.
that's the angle in the first quadrant.
the cosine is negative in the second and third quadrant.
the angle you are looking for is in the third quadrant.
the equivalent angle in the third quadrant is 180 + the reference angle = 180 + 75.52248781 = 255.52248781 degrees.
round that to 1 decimal point and the angle is 255.5 degrees.
here's what it looks like.
