Question

Qual é o seno do ângulo cujo cosx = 0,9.

Answer 1

$\boxed{\begin{array}{l}\sf cos(x)=0,9\\\sf cos(x)=\dfrac{9}{10}\implies cos^2(x)=\dfrac{81}{100}\\\sf sen^2(x)=\dfrac{19}{100}\\\sf sen(x)=\sqrt{\dfrac{19}{100}}\\\sf sen(x)=\dfrac{\sqrt{19}}{10}\end{array}}$