3/4
......................
If

then

The ODE in terms of these series is



We can solve the recurrence exactly by substitution:


So the ODE has solution

which you may recognize as the power series of the exponential function. Then

Answer:
sqrt(2) =x
Step-by-step explanation:
Since this is a right triangle, we can use trig functions
sin theta = opp/ hyp
sin 45 = x/2
2 sin 45 =x
2 ( sqrt(2)/2) =x
sqrt(2) =x