If cosθ= -8/17 and θ is in quadrant iii, cos2θ= and tan2θ=

cos2θ = -0.5563

tan2θ = -1.49.4

Step-by-step explanation:

There are 3 trigonometric ratios; Sine, cosine and tangent.

cos = adjacent/hypotenuse

sine = opposite/hypotenuse  

tangent = opposite/adjacent

If cosθ = -8/17

   θ = cos⁻¹(-8/17)

      = cos⁻¹(-0.4706)

     = 180+61.9

      = 241.9°

cos 2θ = cos (2×241.9)

           = cos 483.8° = cos 123.8°

           = -0.5563

tan 2θ = tan(2×241.9)

           = tan 483.8

           = tan 123.8

            = -1.49.4

i think is g(1)=-1.

hope that i can