Using the identity 2θ+2θ=1sin 2 θ+cos 2 θ=1, find the value of tanθtanθ, to the nearest hundredth, if cosθ=0.42cosθ=0.42 and 3π2<θ<2π23π <θ<2π.

Using the identity 2θ2θ1sin 2 θcos 2 θ1 find the value of tanθtanθ to the nearest hundredth if cosθ042cosθ042 and 3π2ltθlt2π23π ltθlt2π class=

Respuesta :

we know that

The angle theta lies on the IV quadrant

that means ----> the sine and the tangent are negative

so

step 1

Find out the value of the sine

[tex]sin^2\theta+cos^2\theta\text{=1}[/tex]

substitute given value

[tex]\begin{gathered} s\imaginaryI n^2\theta+(0.42)^2=1 \\ s\imaginaryI n^2\theta=1-0.42^2 \\ s\imaginaryI n\theta=-0.91 \end{gathered}[/tex]

step 2

Find out the value of the tangent

[tex]\begin{gathered} tan\theta=\frac{sin\theta}{cos\theta} \\ \\ tan\theta=-\frac{0.91}{0.42} \\ \\ tan\theta=-2.16 \end{gathered}[/tex]

The answer is -2.16