cos/sin/tan

Question

if cos(∅)=0.6347 and 3pi/2≤∅≤2pi

what is sin (∅)=

and tan(∅)=

round to fiur decimal places

Answer 1

3pi/2≤∅≤2pi means that the angle ∅ lies between 270 and 360 degrees both extremities included ie in the 4th Quadrant. In this quadrant, only Cosine and Secant of an angle are positive. The other four trigonometric functions are all negative.

 

sin (∅) = sqrt(1-cos(∅)^2) = - 0.7728

 

tan(∅) = sin(∅)/cos(∅) = -1.2176