Question

me ajudem Tgo=2 preciso saber o coso

Answer 1

$\sin^2\theta+\cos^2\theta=1\\\\\dfrac{\sin^2\theta+\cos^2\theta}{\cos^2\theta}=\dfrac{1}{\cos^2\theta}\\\\\tan^2\theta+1=\dfrac{1}{\cos^2\theta}\\\\\text{Substituindo}\ \tan\theta=2:\\\\(2)^2+1=\dfrac{1}{\cos^2\theta}\\\\5=\dfrac{1}{\cos^2\theta}\\\\\cos^2\theta=\dfrac{1}{5}\\\\\cos\theta=\dfrac{\sqrt{1}}{\sqrt5}\\\\\cos\theta=\dfrac{1}{\sqrt5}\\\\\cos\theta=\dfrac{1}{\sqrt5}\cdot\dfrac{\sqrt5}{\sqrt5}\\\\\boxed{\cos\theta=\dfrac{\sqrt5}{5}}$