Long essay : will mark brainiest !

How and why did relations between the United States and American Indian nations change between 1830 and 1900?

The relations changed between the American Indian Nations and United States due to the Removal Act of 1830 and other Indian Treaties between 1830 to 1900.

Explanation:

Congress constituted to strengthen the foreign trade but to the west of Mississippi river was the Indian tribe or say the American Indian tribes located. Jackson's government provocative of  the idea of Removal Act 1830 by 1830, advocating the removal of Indian tribes from lands which were west to Mississippi.

These lands were now open to white settlers and led to increase in foreign trade thereby. Removal Act 1830, led to the Indian tribe leave their lands and settle to a confined area of present day Oklahoma. they were guaranteed material and financial assistance by the government.

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°

the picture is not clear

explanation: