Answer:
it is not I think...
Step-by-step explanation:
Using the identity
[tex]\cos(2a) = 2 \cos^2(a) - 1[/tex]
We can solve:
[tex]2 \cos^2(a) - 1 = \frac{11}{25}[/tex]
[tex]2 \cos^2(a) = \frac{36}{25}[/tex]
[tex]\cos^2(a) = \frac{18}{25}[/tex]
[tex]\cos(a) = \sqrt \frac{18}{25}[/tex]
[tex]\cos(a) = \sqrt{ 2 \cdot \frac{3^2}{5^2} }= \frac35 \sqrt 2[/tex]
So whoever asked the question forgot the factor 2!!!
Or did I miss anything??
