Question

sendo sec a=3, calcule o valor da expressão: y= sec a + sena/ cos sec a + cos a

Answer 1

$y=sec(a)+\frac{sen(a)}{cossec(a)}+cos(a)\\\\y=sec(a)+sen(a)*\frac{1}{cossec(a)}+cos(a)\\\\y=sec(a)+sen(a)*sen(a)+cos(a)\\\\y=sec(a)+sen^2(a)+cos(a)\\\\y=sec(a)+1-cos^2(a)+cos(a)\\\\y=sec(a)+1-\frac{1}{sec^2(a)}+\frac{1}{sec(a)}\\\\y=3+1-\frac{1}{9}+\frac{1}{3}=\frac{27+9-1+3}{9}=\frac{38}{9}$