Question

the terminal side of an angle in standard position coincides with the line x-2y=0 in quadrant 3, find cosine theta to the nearest ten-thousandth

Answer 1

since the slope of the line is 1/2, tanθ = 1/2 = y/x.

Now draw that triangle in QIII and you can see that cosθ = x/r = -2/√5