I would help but I can’t graph it on here :\
To get you answer multiply .3 and 2.7
The cosine repeats itself every 360 degrees, and it mirrors at 0 and 180 degrees. It inverts around 90 and 270.
So without using a calculator, you can tell that:
cos(520)=cos(520-360)=cos(160)
cos(160) = cos(180-20) = cos(180+20) = cos(200)
cos(160) is NOT equal to cos(20), it would be -cos(20).
cos(160) = -cos(20) = -cos(-20)
So C is the only one unequal.
Since the x-coordinate does not change, we know immediately that this straight line is a vertical one. It does not have a slope (div. by zero is undefined).
The equation of this vertical line is x=0.
The line has no y-intercept.
A line perpend. to the given line has a slope of 0.
