Discuss how rivers help geographers understand how civilization developed.

Explanation:

Civilizations developed around rivers because their waters provided a place to drink and hunt such things as fish and hunt wounding animals who came for a drink. The people would use the water from the rivers for farming.

the images of war are haunting

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°