Answer:
a wild guess would be...56/81
Step-by-step explanation:
This is only right if the triangle is rectangular !
First try to figure out what the length of the other side of the triangle is with the Pythagorean theorem (=> a^2 = b^2 + c^2).
<=> a^2 - c^2 = b^2
=> 9^2 - 5^2 = b^2
<=> 81 - 25 = b^2 = 56
therefor b = the square root of 56.
Next you try to figure out what the cosinus of that angle would be.
the square root of 56/9
Now must you multiply that by two;
112/9
Because this is not an option maybe we need to do something like;
(square root of 56/9)^2
that would equal
56/81
which is the last option.
I do not understand it very much myself so have fun trying to find the correct answer.
