<span>y" + 9y = 0
m^2 + 9 = 0
m = ± 3i
yH = C1 cos 3t + C2 sin 3t
yP = C3 t sin 3t + C4 t cos 3t
hope this helps </span>
Answer:
and 
Step-by-step explanation:
Assume that the terminal side of thetaθ passes through the point (−12,5).
In ordered pair (-12,5), x-intercept is negative and y-intercept is positive. It means the point lies in 2nd quadrant.
Using Pythagoras theorem:




Taking square root on both sides.

In a right angled triangle




In second quadrant only sine and cosecant are positive.
and 
Since the interior angles of a triangle equal 180°, then 180-45=135.
Then you would use 135 to find the remaining two angles: b+3b=135.
4b=135.
Divide to find b. And the plug in whatever b is for the to figure out Angles B and C.
However, I believe the equation it's looking for is: 180=45+b+3b OR 45+4b=180
With 5 elements in A={20,1,6,10,11}, there are 2^5=32 possible subsets, including
the null set, and A itself.
Any subset that is identical to A is NOT a proper subset.
Therefore there are 31 proper subsets, plus the subset {20,1,6,10,11}.
The subsets are:
null set {} (has no elements) ........total 1
{20},{1},{6},{10},{11}.......................total 5
{20,1},{20,6}...{10,11}.....................total 10
{20,1,6},{20,1,10},...{6,10,11}.........total 10
{20,1,6,10}...{1,6,10,11}.................total 5
{20,1,6,10,11}.................................total 1
Altogether 32 subsets.