Answer:
Step-by-step explanation:
Cos(Ф) = Adj / Hyp
Cos(Ф) = Adj / 5
use Pythagoras's
[tex]5^{2}[/tex] = [tex]2^{2}[/tex] +[tex]x^{2}[/tex]
25 - 4 = [tex]x^{2}[/tex]
21 = [tex]x^{2}[/tex]
[tex]\sqrt{21}[/tex] = x
Cos(Ф) = [tex]\sqrt{21}[/tex] / 5
(using the square root means the answer is exact. so leave it like that.)
