How does identifying the main idea help to determine the author's purpose on a topic?

it helps because you can determine the writers perspective which will lead to the purpose.

Explanation:

The main idea of a paragraph is the primary point or concept that the author wants to communicate to the readers about the topic. in a paragraph, when the main idea is stated directly, it is expressed in what is called the topic sentence.

uncanny would be like unlucky or disaster. you can look for more in the dictionary or if you have text book then turn to a. 17 but it's different with textbooks.