Question

3. Error Analysis A classmate began an indirect

proof as shown below. Explain and correct
your classmate's error.
Given: AABC
Prove: LA is obtuse.
Assume temporarily that LA is acute.

Answer 1

Assume angle A is acute or a right angle.

Explanation:

You would say:

Assume angle A is acute or a right angle.

Since acute is not the only opposite of obtuse, you also list the other possibility (which is a right angle).

An obtuse angle is greater than 90 degrees, an acute is less than an obtuse angle and so is a right angle which measures exactly 90 degrees and doesn't go over 90.

Therefore, you would say assume angle A is acute OR a right angle.

Answer 2

Given AABC i think