Good evening.
This is a
incomplete quadratic equation, because it does not have the term
bx. Therefore, we can solve this faster with the following strategy:

Add
16 to both sides:

Take the square root:

Therefore:
To solve for the longest side, the hypotenuse, you have to use the pythagorean theorem. It will be 10^2 + 9^2 = c^2. 100 + 81 =c^2.
c^2 = 181 so c = sqrt(181).
to find sin of A do opposite/hypotenuse which gives you 9/sqrt(181)
to find cos of A do adjacent/hypotenuse which gives you 10/sqrt(181)
So, 6/7*56/1
56*6/7
336/7
the answer is 48