Answer: 3rd century BC
Explanation: Hellenistic astronomy established the roughly spherical shape of Earth as a physical fact and calculated the Earth's circumference.
Answer:
1) Black people were denied their rights and freedom in the South by being segregated. Black people were also denied right by being treated lesser than whites. Another way they were denied proper rights is that they were paid less. Black people were treated lesser by being segregated, or seperated, based on skin colour. There were certain schools and water fountains and restauraunts that were only for black people, and likewise for white people.
*You can add info from your lesson
That would be radar.
This was a key battle between Britain's RAF (Royal Air Force) and the Luftwaffe, if the Germans would've won most likely Britain would've been German; and many different outcomes could've happened in the past.
But, since radar was invented, and the British employed it in their tactics; that along with the communication between them helped repel the attack in the Battle of Britain.