Which side, north or south attacked first

The Battle of Fort Sumter (April 12–13, 1861) was the bombardment of Fort Sumter near Charleston, South Carolina by the Confederate States Army, and the return gunfire and subsequent surrender by the United States Army, that started the American Civil War.

angle a = 40.6°

step-by-step explanation:

for any right angle triangle we know the pythagoras theorem reveals

hypotenuse² = height²+base²

by this formula we will calculate the length of hypotenuse

h² = 6²+7²

⇒ h =√36+49 = √85 = 9.22

now from the given triangle sin a = height/ hypotenuse

                                                sin a = 6/9.22 = 0.651

therefore

so angle a = 40.6°

demand is the need and oportunity to buy a given good or service.