use the following information to determine sin2x, cos2x, tan2x, tanx= -3, cos x is positive

Answer 1

tanx=-3

use arctan on your calculator

tan is -3 at x=-71.565°

2x=-143.13°

use your calculator to find the 3 values

sin2x=sin(-143.13)=-0.6

cos 2x=cos(-143.13)=-0.79999=-0.8

tan2x=tan(-143.13)=0.75

Answer 2

Hi Mr. B,

Let's start with the given information:

tan(x) = -3

cos(x) > 0

tan(x) is the slope ratio, so if it is negative, we must be in Quadrant II or Quadrant IV

cos(x) is the base length of the unit triangle, so if it is positive, we must be in Quadrant I or Quadrant IV

This information tells us we must be in Quadrant IV

Now we can solve for x:

tan(x) = -3

arctan(tan(x)) =arctan(-3)

x = -1.25 radians

Now we can use x = -1.25 to evaluate sin(2x), cos(2x), and tan(2x)

sin(2*-1.25) = -.60

cos(2*-1.25) = -.80

tan(2*-1.25) = .75