Greetings from Brasil...
Here we have application of Trigonometry
COS β = adjacent side ÷ hypotenuse (H)
bringing to our problem....
COS A = AC ÷ H
But we dont have AC.... We have to use Pitagoras:
AB² = AC² + BC²
AC² = AB² - BC²
AC = √(AB² - BC²)
AC = √(10² - 8²)
AC = √(100 - 64)
AC = √36
So
COS A = AC ÷ H ⇔ COS A = AC ÷ AB
COS A = 6/10
Answer: B) 3/5
Step-by-step explanation:
Cos = adjacent/hypotenuse
Thus, the cos is AC/AB.
Because of Pythagorean Theorem, AC^2=AB^2-BC^2. Let AC be x.
[tex]x^2=10^2-8^2\\x^2=100-64\\x^2=36\\x=6[/tex]
Thus, the cos is 6/10, or 3/5
