cos(198)

<-- Enter angle or number for inverse functions. Enter PI for π


Calculate cos(198)°
Since our angle is greater than 180 and less than or equal to 270 degrees, it is located in Quadrant III
In the third quadrant, the values for tan are positive only.

198 is an obtuse angle since it is greater than 90°

cos(198) = -0.39

In Microsoft Excel or , you write this function as =COS(RADIANS(198))

Since 198° is less than 90, we can express this in terms of a cofunction
cos(θ) = sin(90 - θ) = sin(90 - 198) = sin(-108)

Important Angle Summary
θ°θradianssin(θ)cos(θ)tan(θ)csc(θ)sec(θ)cot(θ)
0010010
30°π/61/23/23/322√3/33
45°π/42/22/21221
60°π/33/21/232√3/323/3
90°π/210N/A10N/A
120°2π/33/2-1/2-√32√3/3-2-√3/3
135°3π/42/2-√2/2-12-√2-1
150°5π/61/2-√3/2-√3/32-2√3/3-√3
180°π0-100-1N/A
210°7π/6-1/2-√3/2-√3/3-2-2√3/3-√3
225°5π/4-√2/2-√2/21-√2-√21
240°4π/3-√3/2-1/2-√3-2√3/3-2-√3/3
270°3π/2-10N/A-10N/A
300°5π/3-√3/21/2-√3-2√3/32-√3/3
315°7π/4-√2/22/2-1-√22-1
330°11π/6-1/23/2-√3/3-22√3/3-√3