Why did Nelson Mandela eventually believe violence was necessary

Which of the following terms describes the layers of air surrounding the earth ?

Which of the following best describes brazil's economy from 1650-1880? a. it gradually shifted to manufacturing as the industrial revolution progressed. b. it was based on mining. c. it was based on plantation agriculture, where slaves served as a labor force. d. it was based on small, family-owned farms.

In the diagram below, ab and bc are tangent to o. what is the measure of