Question

Sandra knows the Pythagorean identity sin 2 ⁡ θ + cos 2 ⁡ θ = 1 . If she is told that 0 ≤ θ ≤ π 2 and cos ⁡ θ = 5 12, what will she get when she correctly calculates tan ⁡ θ ?

Answer 1

Answer:

$\text{tan}(\theta)=\frac{\sqrt{119}}{5}$

Step-by-step explanation:

We have been given that Sandra knows the Pythagorean identity $\text{sin}^2(\theta)+\text{cos}^2(\theta)=1$. She is told that $0\leq \theta\leq \frac{\pi}{2}$ and $\text{cos}(\theta)=\frac{5}{12}$.

First of all, we will find value of sine theta using the given identity.

$\text{sin}^2(\theta)+\text{cos}^2(\theta)=1$

$\text{sin}^2(\theta)+(\frac{5}{12})^2=1$

$\text{sin}^2(\theta)+\frac{25}{144}=1$

$\text{sin}^2(\theta)+\frac{25}{144}-\frac{25}{144}=1-\frac{25}{144}$

$\text{sin}^2(\theta)=\frac{144-25}{144}$

$\text{sin}^2(\theta)=\frac{119}{144}$

$\text{sin}(\theta)=\sqrt{\frac{119}{144}}$

$\text{sin}(\theta)=\frac{\sqrt{119}}{12}$  

$\text{tan}(\theta)=\frac{\text{sin}(\theta)}{\text{cos}(\theta)}$

$\text{tan}(\theta)=\frac{\frac{\sqrt{119}}{12}}{\frac{5}{12}}$

$\text{tan}(\theta)=\frac{\sqrt{119}*12}{5*12}=\frac{\sqrt{119}}{5}$

Therefore, $\text{tan}(\theta)=\frac{\sqrt{119}}{5}$.